electronic load elp/slm - et system...elp/slm 100/400/cxx 10000 1-400 doc: elp/slm/1002 page 4 of 48...

Operating Manual

Electronic Load ELP/SLM

Your actual unit may differ from that shown

CONTENTS

1. About this Manual.........................................................................................................4 Scope of Manual .......................................................................................................4 Options Available .....................................................................................................4

2. Goods Inwards Inspection.............................................................................................5 Visual Inspection ......................................................................................................5

3. Installation.....................................................................................................................5 Mains Operation........................................................................................................5 Mains Socket and Fuse .............................................................................................5

4. Power Terminals ...........................................................................................................6 Input Sockets.............................................................................................................6 Back Panel Input Terminals......................................................................................6

5. Sense Mode...................................................................................................................7 6. Front Panel Operation ...................................................................................................8

Initial Start Up...........................................................................................................8 Current Presetting .....................................................................................................8 Current Setting ..........................................................................................................9 Resistance Presetting ................................................................................................9 Resistance Setting .....................................................................................................9 Calculating RMIN .....................................................................................................10

7. Analogue Interface......................................................................................................11 SUB-D 25 Pin Assignment .....................................................................................12 Types of Analogue Interface...................................................................................12 Setting the Operating Mode ....................................................................................13 Setting the Load Current .........................................................................................13 Setting the Load Resistance ....................................................................................14 Operating the Standby Function .............................................................................16 Voltage Monitor......................................................................................................16 Current Monitor ......................................................................................................17 Fault Signal .............................................................................................................17 Constant Current Signal..........................................................................................17 Constant Resistance Signal .....................................................................................18 Standby Function Signal .........................................................................................18

8. IEEE 488.2 / RS232 Interface Setup...........................................................................19 Selecting the System Operating Mode....................................................................19 Setting the 8-Way DIP Switch (IEEE 488.2 Operation).........................................20 IEEE 488.2 Permissible Addresses.........................................................................21 IEEE488.2 BUS Capabilities ..................................................................................22 IEEE 488.2 Socket Assignment ..............................................................................22 Setting the 8-Way DIP Switch (RS232 Operation) ................................................23 RS232 Socket Assignment......................................................................................23

Doc: ELP/SLM/1002 Page 2 of 48

9. IEEE 488.2 / RS232 Programming Format ................................................................24

Numerical Values....................................................................................................24 Use of Letters ..........................................................................................................24 Terminators and Delimiters ....................................................................................25 Changing the Range of a Parameter........................................................................25 Command Sequence................................................................................................26

10. Standard IEEE488.2/RS232 Interface Functions........................................................27 Standby Function ....................................................................................................27 Constant Current Mode...........................................................................................27 Setting the Load Current .........................................................................................28 Constant Resistance Mode......................................................................................28 Setting the Resistance Value...................................................................................29 Measuring Functions...............................................................................................30 Status Enquiry.........................................................................................................30 Unit Version Enquiry..............................................................................................30 DI Function .............................................................................................................31 Error Messages........................................................................................................32

11. Dynamic Functions .....................................................................................................33 Selecting Dynamic Operation .................................................................................33 Constant Voltage Operation....................................................................................34 Constant Power Mode.............................................................................................35 Dynamic Waveforms ..............................................................................................36 Square Wave ...........................................................................................................36 Programming a Square Wave .................................................................................37 Pulse Width Adjustment .........................................................................................37 Triangular Wave .....................................................................................................38 Programming a Triangular Wave............................................................................39 Sinewave .................................................................................................................40 Programming a Sinewave .......................................................................................41 Current Rise Time Adjustment ...............................................................................41

12. Other Options Available .............................................................................................42 Built in PSU (Option /OV) .....................................................................................42 Built in Power Relay (Option /OR) ........................................................................43

13. Commands for IEEE488.2 and RS232 .......................................................................44 14. Technical Data ............................................................................................................45 15. Front Panel View ........................................................................................................46 16. Rear Panel View .........................................................................................................47 17. Service and Support ....................................................................................................48


1. About this Manual This manual aims to provide clear and concise information regarding the operation of your unit. Please ensure that you read this manual prior to operating your unit as it contains important safety guidelines. You should retain these instructions for future reference.

Scope of Manual This guide is applicable to all ET’s Electronic Loads with the part number ELP/SLM. The following table details ET’s standard Loads to which this manual applies.

Part Number Power (W) Voltage (VDC) ELP/SLM 10/60/Cxx 1000 1-60 ELP/SLM 10/100/Cxx 1000 1-100 ELP/SLM 10/200/Cxx 1000 1-200 ELP/SLM 10/400/Cxx 1000 1-400 ELP/SLM 15/60/Cxx 1500 1-60 ELP/SLM 15/100/Cxx 1500 1-100 ELP/SLM 15/200/Cxx 1500 1-200 ELP/SLM 15/400/Cxx 1500 1-400 ELP/SLM 20/60/Cxx 2000 1-60 ELP/SLM 20/100/Cxx 2000 1-100 ELP/SLM 20/200/Cxx 2000 1-200 ELP/SLM 20/400/Cxx 2000 1-400 ELP/SLM 30/60/Cxx 3000 1-60 ELP/SLM 30/100/Cxx 3000 1-100 ELP/SLM 30/200/Cxx 3000 1-200 ELP/SLM 30/400/Cxx 3000 1-400

The code /Cxx indicates the current limit to which thnumber includes the code C50 then your Electronic L

Options Available The following list details the standard options avwill include the option code if it has been fitted.options. Please contact your local ET office for

Option Code D/ATE No front panel display or control/AI Analogue interface for control an/ATI Isolated analogue interface for c/L IEEE 488.2 interface with listene/LT IEEE 488.2 interface with both li/LRS RS232 interface with listener fun/LTRS RS232 interface with both listen/L+LRS IEEE 488.2 and RS232 interface/LT+LTRS IEEE 488.2 and RS232 interface/DYN-L Dynamic functions operable via /DYN-B Dynamic functions operable via /DYN-LB Dynamic functions operable via /OV Built in power supply to run full l/OR Built in power relay for real shor

ELELELELELELELELELELELELELELELEL

Doc: ELP/SLM/1002

Part Number Power (W) Voltage (VDC) P/SLM 40/60/Cxx 4000 1-60 P/SLM 40/100/Cxx 4000 1-100 P/SLM 40/200/Cxx 4000 1-200 P/SLM 40/400/Cxx 4000 1-400 P/SLM 50/100/Cxx 5000 1-100 P/SLM 50/200/Cxx 5000 1-200 P/SLM 50/400/Cxx 5000 1-400 P/SLM 65/100/Cxx 6500 1-100 P/SLM 65/200/Cxx 6500 1-200 P/SLM 65/400/Cxx 6500 1-400 P/SLM 80/100/Cxx 8000 1-100 P/SLM 80/200/Cxx 8000 1-200 P/SLM 80/400/Cxx 8000 1-400 P/SLM 100/100/Cxx 10000 1-100 P/SLM 100/200/Cxx 10000 1-200 P/SLM 100/400/Cxx 10000 1-400

e unit has been set. For example if your part oad has a range of 0-50A.

ailable for your unit. Your part number It is possible to retrofit many of these details.

escription . Analogue interface fitted d measurement ontrol and measurement r function only stener and talker functions ction only

er and talker functions s with listener functions only s with both listener and talker functions

the front panel only IEEE 488.2 and/or RS232 interfaces only front panel controls and by BUS oad from 0Vdc t circuit

Page 4 of 48

2. Goods Inwards Inspection Before unpacking the unit, please ensure that the packing box that the unit is shipped in is free of damage. If external damage is found it is important that you record what you have seen. It is vital that the packing box be kept safe in case a claim has to be made. If no damage is found you should still retain all packaging materials to ensure the unit is adequately protected in case it needs to be transported in the future.

Visual Inspection Your unit left the factory in perfect condition and was thoroughly inspected and fully tested prior to dispatch. However, upon delivery of the unit, it must be checked to ensure that the unit was not damaged during transit. Such damage may take the form of loose or broken control knobs and bent or broken connectors. Do not use the unit if any physical damage is apparent. Please inform the carriers and a representative of ET immediately.

3. Installation To reduce the risk of electric shock and early product failure your instrument should be installed in a temperature and humidity controlled indoor environment. Do not expose this unit to rain or moisture as personal injury may result. The ambient temperature must not exceed 50°C.

Mains Operation If your unit is not fitted with a wide input it must be ensured that the voltage selector is correctly positioned. The selector switch is usually situated on the rear panel of the unit. The following settings are possible:

230 for 230VAC –10%, +15% at 50/60Hz 115 for 115VAC –10%, +15% at 50/60Hz

Any damage caused by using the incorrect input voltage or frequency will invalidate the unit’s warranty.

Mains Socket and Fuse The mains socket for the DIN plug is located at the rear of the unit. The mains input fuse (0.5 AT) is found directly underneath the mains socket. If your unit is fitted with the option /OV (built in PSU for operation from 0V) you must replace the fuse with the same type and make.


4. Power Terminals This section contains information on the connections that need to be made between the Electronic Load and the unit under test.

Input Sockets The voltage and current range of your unit dictates the type of input sockets fitted. For lower power applications the terminals on the front panel can be used. Units with a higher power range will also have sockets fitted to the rear panel of the unit. Please refer to the following table if you are unsure as to which input sockets should be used.

Current Voltage Type of Connectors Socket Location 60V High power current rails Back panel

Ensure that the correct terminals are used for your application. Using the wrong input sockets for high power loading will result in damage to the unit

Back Panel Input Terminals Please take special care when connecting the unit under test to the terminals on the rear panel. In addition to the input terminals a pair of threaded sense terminals are provided on the rear panel to enable voltage losses in the cables to be compensated for.

Ensure that the load lines are connected to the (+) positive and (-) terminals. DO NOT CONNECT THE LOAD LINES TO THE SENSE TERMINALS

The unit is supplied with factory fitted links between the positive input (+) and positive sense (+S) and the negative input (-) and negative sense (-S). If sense mode is required then the links should be removed and the cables attached individually.

Doc: E

THE TERMINALS (+) POSITIVE AND (+S) POSITIVE SENSE AND(-) NEGATIVE AND (-S) NEGATIVE SENSE MUST BE BRIDGEDIF SENSE OPERATION IS NOT REQUIRED.

LP/SLM/1002 Page 6 of 48

5. Sense Mode The sense terminals can be used to avoid voltage losses in the cables between the Electronic Load and the unit under test. A maximum of 1V can be compensated for. To use this feature please adhere to the following procedure:

III.

Remove the factory fitted links found on the rear terminal block, between negative sense (-S) and the negative input (-) and positive sense (+S) and

the positive input (+).

Connect the +S and –S terminals to the respective positive and negative terminals of the unit under test. It is only necessary to use a small diameter

cable, as only a signal level current will flow.

Connect the positive (+) and negative (-) power inputs to the load ensuring that the cables are of a sufficiently large cross sectional area, to handle the

current being drawn.

I.

Retain the links for future use such as when the sense mode is not required.

II.

The unit can now measure the difference between the set voltage and the voltage at the unit under test, compensating accordingly up to a maximum of 1V.

THE TERMINALS (+) POSITIVE AND (+S) POSITIVE SENSE AND(-) NEGATIVE AND (-S) NEGATIVE SENSE MUST BE BRIDGEDIF SENSE OPERATION IS NOT REQUIRED.

Failure to replace the links when the sense mode is not being used willmean the voltage and current inputs are not displayed on the frontpanel.

TO ENSURE SAFE OPERATION OF THE UNIT YOU MUSTREPLACE THE LINKS IF SENSE MODE IS NOT BEING USED.


6. Front Panel Operation This section details the functions on the front panel of the unit. If the part number of the unit includes the code /ATE then no control or measurement via the front panel is possible. In this instance the unit’s functions can only be adjusted by the analogue or GPIB interface. Please refer to those sections if your unit has been built as an /ATE version.

Initial Start Up Connect the unit to a suitable mains supply. The unit is then turned on by pressing the power switch on the front panel. The following is apparent if the “I/R Mode” switch is not operated:

• The unit is in the Constant Current Mode – LED “I-Mode” is illuminated • Unit is in the standby mode – LED “STBY” is illuminated • “V” Display shows the voltage applied to the terminals • “A” Display shows the current that is flowing

If the “I/R Mode” is operated than the following state is visible:

• The unit is in the Constant Resistance Mode – LED “R-Mode” is illuminated • Unit is in the standby mode – LED “STBY” is illuminated • “V” Display shows the voltage applied to the terminals • “A” Display shows the current that is flowing

Current Presetting The current presetting function enables the desired load current to be set without the current being present at the Electronic Load’s input. To preset the current the following procedure should be observed:

Ensure that the unit is in its constant current mode -“I-Mode” LED is lit If “I-Mode” LED not lit then operate “I/R Mode” switch

Ensure that the unit is in not in its standby mode -“STBY” LED is not lit If “STBY” LED is lit then operate “STBY” switch

Depress and hold down the “Standby” button Use the Current potentiometer to preset the load current

The preset current can be read from the “A” Display during adjustment Release the “Standby” switch when desired current is reached Operate the “Standby” switch to allow the Load to sink the preset current

The preset current is now present at the input of the Electronic Load


Current Setting To set the current ensure the Electronic Load is in its constant current mode. If the “I-Mode” LED is not illuminated then operate the “I/R Mode” switch once. The 10-turn “Current” potentiometer can then be used to set the load current from 0A to the unit’s maximum permissible value. The Current being sunk by the Electronic Load is read from the “A” display

Resistance Presetting The resistance presetting function enables the desired load resistance to be set without the current being present at the Electronic Load’s input. To preset the resistance the following procedure should be observed:

Ensure that the unit is in its constant resistance mode -“Ω-Mode” LED is lit If “Ω-Mode” LED not lit then operate “I/R Mode” switch

Ensure that the unit is in not in its standby mode -“STBY” LED is not lit If “STBY” LED is lit then operate “STBY” switch

Depress and hold down the “Standby” button Use the Current potentiometer to preset the load resistance

The preset resistance is read from the “V” Display during adjustment Release the “Standby” switch when desired resistance is reached Press and release the “Standby” switch once more to allow the Load to operate

The preset resistance is now present at the input of the Electronic Load The actual current flowing at the Load’s input can be read from the “A” display. The voltage also present at the Load’s input can be read

from the “V” display.

Resistance Setting The default mode of the unit is constant current operation. To switch to constant resistance operation press the “I/R Mode” switch once. Ensure the “Ω-Mode” LED is illuminated. The 10 turn “Current” potentiometer can now be used to set the resistance in the range from RMIN to RMAX. The actual load current flowing at the Load’s input can be read on the current display "A", the actual voltage present can be read on the "V" voltage display.


Calculating RMIN To calculate the minimum resistance the unit will operate at the following calculation will need to be made:

VMAX 10 * IMAX

RMIN = Where; RMIN = Smallest resistance value that can be set

VMAX = Unit’s maximum permissible voltage IMAX = Unit’s maximum permissible current

Example: ELP/SL 100/C10. In this instance VMAX = 60V and IMAX = 10A Please refer to section 1 if you are unsure of your unit’s range. Step 1 Step 2 Step 3

∴RMIN = 0.6 Ω RMIN = 60 10 * 10

VMAX 10 * IMAX RMIN =

The maximum resistance of your Electronic Load is infinite.


7. Analogue Interface One of the following codes will be present in your units part number if you have an Analogue Interface; /AI, /ATI, /ATE or /ATE/ATI. If your unit is fitted with an Analogue Interface then the unit’s control and measurement functions can be performed via the SUB-D 25 socket on the rear panel. The unit comes complete with a SUB-D 25 male connector fitted into the socket. The following sketch shows the pin numbering of the SUB-D 25. You will need an accurate external power supply capable of providing 0-5VDC or 0-10VDC depending on the type of analogue interface that you’re unit is fitted with.

Factory Fitted Links Unless an /ATE version has been specified then the default mode of operating the unit is via the front panel controls. If analogue control is required the SUB-D 25 connector must be disconnected from the socket. The cover of the SUB-25 connector should then be removed and the factory fitted links disconnected. The links should be PIN PIN Function replaced as shown if 1 14 front panel operation 2 15 ISET is required 3 16 Standby

4 17 5 18 I/R Mode

6 19 7 20 8 21 9 22 10 23 Analogue Ground 11 24 ( /ATI Only) 12 25 13

Pin 25

Pin 14 Pin 1

Pin 13

If using a galvanically isolated analogue interface (type /ATI) it is essential that you remove the factory fitted link between pins 13 and 23

Remember to retain the removed links for future front panel operation


SUB-D 25 Pin Assignment The following table details the functions assigned to the SUB-D 25 pins. Greyed boxes indicate that the given function is not available with that particular interface.

Function /AI /ATI /ATE /ATE/ATI ISET (front panel) 2 2 Standby (front panel) 4 4 I/R Mode (front panel) 5 5 DGND 6 6 (GI) 14 14 (GI) Ω LED (front panel) 8 R-Mode Readback 9 9 (GI) +5VDC Analogue Reference 10 9 Voltage Input Readback 12 12 (GI) 19 Analogue Ground (a) 13 (GI) 19 (GI) ISET Control 15 15 (GI) 21 10 (GI) Standby Control 17 17 (GI) 5 21 (GI) I/R Mode Control 18 18 (GI) 1 1 (GI) +5VDC Digital Reference 19 19 (GI) 15 15 (GI) CC-Mode Readback 20 20 (GI) 4 (GI) Error LED (front panel) 21 21 (GI) 8 8 (GI) Standby Readback 22 22 5 (GI) Analogue Ground (b) 23 23 10 Current Input Readback 25 25 (GI) 18 18 (GI)

(GI) = Galvanic Isolation

Types of Analogue Interface There are four standard types of Analogue Interfaces available with ET units. Unless a 0-10VDC interface was specified on order your functions will be controlled and you’re measurements readback with 0-5VDC.

/AI - 0-5VDC Analogue Interface for ground based

control and measurement. Unit also fitted with front panel controls.

/ATI - 0-5VDC Isolated Analogue Interface for control

and measurement. Unit also fitted with front panel controls.

/ATE - 0-5VDC Analogue Interface for ground based

control and measurement. Unit has no front panel controls.

/ATE/ATI - 0-5VDC Isolated Analogue Interface for control

and measurement. Unit has no front panel controls. Please refer to your unit’s part number if you are unsure of your analogue interface.


Setting the Operating Mode Changeover between the constant current and constant resistance modes can be made externally by TTL signal. Firstly, remove the factory fitted link on the SUB-D 25 plug between pins 5 and 18. The constant current mode is the default mode of operation. To operate the unit in its constant resistance mode connect the I/R Mode Control Pin to the digital reference.

Function /AI /ATI /ATE /ATE/ATI I/R Mode Control 18 18 (GI) 1 1 (GI) +5VDC Digital Reference 19 19 (GI) 15 15 (GI) A high signal (+5V) causes the unit to operate in the constant resistance mode. Conversely, a low signal (0V) ensures the ELP/SL is in its constant current mode.

Setting the Load Current To set the level of current that the Electronic Load is to sink via the analogue interface you must firstly remove the factory fitted link between pins 2 and 15. Ensure that the unit is operating in its constant current mode by disconnecting any link between the I/R Mode Control Pin and the digital reference. The positive line of the external power supply is connected to the ISET Control pin of the Analogue Interface while the ground line is connected to the analogue ground pin.

Function /AI /ATI /ATE /ATE/ATI ISET Control 15 15 (GI) 21 10 (GI) Analogue Ground (a) 13 (GI) 19 (GI) Analogue Ground (b) 23 23 10 It is now possible to set the Load current proportionally with an external control voltage of 0-5VDC. The full 5VDC will set the unit to accept the maximum permissible current. Example: ELP/SL 100/C10 Maximum current =10A 5.0VDC control voltage corresponds to 10A input current 2.5VDC control voltage corresponds to 5A input current 1.0VDC control voltage corresponds to 2A input current


Setting the Load Resistance To set the Load Resistance you must firstly remove the factory fitted link between pins 2 and 15. The unit needs to be operating in its constant resistance mode so connect the I/R Mode Control Pin to the digital reference. The positive line of the external power supply is connected to the ISET Control pin of the Analogue Interface while the ground line is connected to the analogue ground pin.

Function /AI /ATI /ATE /ATE/ATI ISET Control 15 15 (GI) 21 10 (GI) Analogue Ground 13 (GI) 19 (GI) Analogue Ground 23 23 10 You will have a minimum resistance that can be set depending on the Electronic Load’s range. The formula used to calculate the minimum resistance that your Load will operate at follows:

VMAX

10 * IMAX RMIN =

Where; RMIN = Smallest resistance value that can be set

VMAX = Unit’s maximum permissible voltage IMAX = Unit’s maximum permissible current

So for example: ELP/SL 200/C20. In this instance VMAX = 60V and IMAX = 20A Please refer to your part number and section 1 if you are unsure of your unit’s range. Step1 Step 2 Step 3

∴RMIN = 0.3Ω RMIN = 60 10 * 20

VMAX 10 * IMAX RMIN =


The following formula is used to calculate the control voltage needed to set a given resistance value. You will again need to know the maximum current and voltage ranges of your Electronic Load. Please refer to your part number and the table in section 1 if you are unsure of your unit’s range.

VMAX 1 2 * IMAX R VPROG =

Where; VPROG = External voltage need

VMax = Unit’s maximum permIMax = Unit’s maximum perm

R = Resistance value to be Example: ELP/SL 200/C5. In this instance VMAX = 60V and IMAX = 5A Desired resistance setting = 10Ω Step 1 Step 2

VPROG = 60 2 * 5 *

VMAX 1 2 * IMAX 10 * VPROG =

Thus the programming voltage that needs to be appl0.6VDC

Doc: ELP/SLM/1002

*

ed to set resistance issible voltage issible current set

Step 3

∴VPROG = 0.6V 1 10

ied for a constant resistance of 10Ω is

Page 15 of 48

Operating the Standby Function To operate the standby function via the analogue interface it is necessary to remove the factory fitted link between Standby (pin 4) and Standby Control (pin 17). To release or activate the Standby mode a relay contact should be fitted between Standby Control and Digital Ground as shown in the table below.

Function /AI /ATI /ATE /ATE/ATI DGND 6 6 (GI) 14 14 (GI) Standby Control 17 17 (GI) 5 21 (GI) The Standby function is triggered by a falling slope, consequently each closing action of the contact changes the standby status.

Voltage Monitor An analogue signal is available to indicate the voltage being sunk by the Electronic Load. The monitor voltage can be tapped between the Voltage Readback pin and Analogue Ground.

Function /AI /ATI /ATE /ATE/ATI Voltage Input Readback 12 12 (GI) 19 Analogue Ground (a) 13 (GI) 19 (GI) Analogue Ground (b) 23 23 10 Example: ELP/SL 801/C50 Maximum Voltage = 100VDC 5.0VDC monitor voltage corresponds to 100V input voltage 2.5VDC monitor voltage corresponds to 50V input voltage 1.0VDC monitor voltage corresponds to 20V input voltage


Current Monitor An analogue signal is available to indicate the current being sunk by the Electronic Load. The monitor current can be tapped between the Current Readback pin and Analogue Ground.

Function /AI /ATI /ATE /ATE/ATI Current Input Readback 25 25 (GI) 18 18 (GI) Analogue Ground (a) 13 (GI) 19 (GI) Analogue Ground (b) 23 23 10 Example: ELP/SL 801/C50 Maximum Current = 50A 5.0VDC monitor voltage corresponds to 50A input current 2.5VDC monitor voltage corresponds to 25A input current 1.0VDC monitor voltage corresponds to 10A input current

Fault Signal If an error occurs such as overtemperature or undervoltage a fault signal will be present between the Error pin and Digital Ground.

Function /AI /ATI /ATE /ATE/ATI Error 21 21 (GI) 8 8 (GI) DGND 6 6 (GI) 14 14 (GI)

A high signal (+5V) indicates that there is no fault. Conversely, a low signal (0V) means that an error has occurred.

Constant Current Signal A signal is available to check whether the unit is in its constant current mode.

Function /AI /ATI /ATE /ATE/ATI CC-Mode Readback 20 20 (GI) 1 4 (GI) DGND 6 6 (GI) 14 14 (GI) A low signal will be measured (0V) between the given pins if the unit is operating in constant current mode. Constant current operation for /ATE only units is signified by a high signal (+5V) between pins 1 and 14.


Constant Resistance Signal To determine if the unit is operating in its constant resistance mode a signal between the following pins is available.

Function /AI /ATI /ATE /ATE/ATI R-Mode Readback 9 9 (GI) I/R Mode Control 1 1 (GI) DGND 6 6 (GI) 14 14 (GI)

A low signal will be measured (0V) between the given pins if the unit is operating in constant resistance mode.

Standby Function Signal The status of the standby function can be checked from the analogue interface.

Function /AI /ATI /ATE /ATE/ATI Standby Readback 22 22 5 (GI) Standby Control 5 DGND 6 6 (GI) 14 14 (GI)

A low signal (0V) indicates that the standby function is on. A high signal (+5V) will be measured if the standby function is off thus signifying that the input to the Electronic Load has been released.


8. IEEE 488.2 / RS232 Interface Setup This section details the optional computer interface that maybe fitted to your unit. Before interface control and / or measurement can be achieved you will need to ensure that your PC and the test instrument can successfully communicate with each other. If you are unsure of the type of interface you have fitted or its functionality please refer to your unit’s part number and the table below.

Option Code Description /L IEEE 488 interface with listener function only

/LT IEEE 488 interface with both listener and talker functions /LRS RS232 interface with listener function only

/LTRS RS232 interface with both listener and talker functions /L+LRS IEEE 488 and RS232 interfaces with listener functions only

/LT+LTRS IEEE 488 and RS232 interfaces with both listener and talker functions

Selecting the System Operating Mode If your unit is fitted with a computer interface than an 8-way DIP switch can be found on the rear panel. The system mode is set by switch number 8. The switch is only recognised when the unit is turned on. Therefore the unit must always be switched off and then on again when there has been any change in the position of the switch.

O N D I P 1 2 3 4 5 6 7 8

DIP Switch No. 8 Controls the system mode as follows:

ON - RS232 Operation Only OFF - IEEE 488.2 or Front Panel Operation

In RS232 mode front panel operation can only be achieved once DIP switch number 8set to off and the unit turned off and then on again. In IEEE 488.2 mode the ‘local’ button on the front panel can be used to enable front panel

is

operation. Once the next IEEE ommand is sent the unit will revert back to BUS control.

s depending on whether the EE 488.2 or the RS232 operating mode has been selected.

c The 7 remaining DIP switches are allocated different functionIE


Setting the 8-Way DIP Switch (IEEE 488.2 Operation) In the IEEE 488.2 mode switches 6 and 7 have no function. In other words their switched position has no meaning. Switches 1 to 5 are used to set the device address on the IEEE 488.2 BUS. The factory set address is 5 as shown in the following diagram. O N D I P

1 2 3 4 5 6 7 8

Addresses from 1 to 30 are possible. Should an invalid address be set, such as 0 or 31, all the LED’s will flash. If such an error occurs a valid address must be entered and the device switched off and then on again. The device address is set in binary code. When the switch is in the OFF position, the associated bit has the value 1. In the ON position, the associated bit has the value 0. The table below illustrates the switch number and its associated decimal number when in the OFF position.

Switch No. 1 2 3 4 5 Decimal No. 1 2 4 8 16

For example: If the unit address is to be set to 6.

6 = 4 + 2 Thus switch 3 (value 4) and switch 2 (value 2) must be in the OFF position. Switches 5, 4 and 1 must be in the ON position.


IEEE 488.2 Permissible Addresses To simplify the setting, a list of all permitted unit addresses and the associated switch positions is given below. The factory set address is 5.

Device Address

Switch No. 5

Switch No. 4

Switch No. 3

Switch No. 2

Switch No. 1

Listener Address

Talker Address

Device Address

1 ON ON ON ON OFF ! A 1 2 ON ON ON OFF ON “ B 2 3 ON ON ON OFF OFF # C 3 4 ON ON OFF ON ON $ D 4 5 ON ON OFF ON OFF % E 5 6 ON ON OFF OFF ON & F 6 7 ON ON OFF OFF OFF ‘ G 7 8 ON OFF ON ON ON ( H 8 9 ON OFF ON ON OFF ) I 9

10 ON OFF ON OFF ON * J 10 11 ON OFF ON OFF OFF + K 11 12 ON OFF OFF ON ON , L 12 13 ON OFF OFF ON OFF - M 13 14 ON OFF OFF OFF ON . N 14 15 ON OFF OFF OFF OFF / O 15 16 OFF ON ON ON ON 0 P 16 17 OFF ON ON ON OFF 1 Q 17 18 OFF ON ON OFF ON 2 R 18 19 OFF ON ON OFF OFF 3 S 19 20 OFF ON OFF ON ON 4 T 20 21 OFF ON OFF ON OFF 5 U 21 22 OFF ON OFF OFF ON 6 V 22 23 OFF ON OFF OFF OFF 7 W 23 24 OFF OFF ON ON ON 8 X 24 25 OFF OFF ON ON OFF 9 Y 25 26 OFF OFF ON OFF ON : Z 26 27 OFF OFF ON OFF OFF ; [ 27 28 OFF OFF OFF ON ON < 28 29 OFF OFF OFF ON OFF = ] 29 30 OFF OFF OFF OFF ON > ^ 30


IEEE488.2 BUS Capabilities The IEEE 488.2 BUS interface was implemented with the GPIB Controller upd, NEC 7210. The following interface functions in accordance with IEC 625 are available:

Function Description Capability SH1 Source Handshake All functions AH1 Acceptor Handshake All functions T6 Talker Basic equipment, serial poll, end addressing with MLA L4 Listener Basic equipment, end addressing with MLA

SR1 Service Request All functions RL1 Remote Local All functions PP1 Parallel Poll All functions (with interlocking LLD) DC1 Device Clear Setting remotely controlled DTO Device Trigger No capability CO Controller No capability

Connection to the BUS is made via a 24 pin plug-type connector in accordance with the IEEE 488.2 standard.

IEEE 488.2 Socket Assignment The following table details the pin assignment for the IEEE 488.2 socket.

Function Pin No. Pin No. Function LOG.GND 24 12 SHIELD GND 11 23 11 ATN GND 10 22 10 SRQ GND 9 21 9 IFC GND 8 20 8 NDAC GND 7 19 7 NRFD GND 6 18 6 DAV REN 17 5 EOI DIO8 16 4 DIO4 DIO7 15 3 DIO3 DIO6 14 2 DIO2 DIO5 13 1 DIO1


Setting the 8-Way DIP Switch (RS232 Operation) If the unit is operating via the serial interface in RS232 mode then switches 7,6 and 5 on the 8-Way DIP switch are used to set the transfer speed. The following table shows the switch positions and their effect on the rate of data exchange. Switch No. 7 Switch No. 6 Switch No.5 Baud Rate

ON ON ON 75 ON ON OFF 150 ON OFF ON 300 ON OFF OFF 600 OFF ON ON 1200 OFF ON OFF 2400 OFF OFF ON 4800 OFF OFF OFF 9600

Switches 1, 2, 3 and 4 have no function and thus have no effect on the baud rate. Other interface parameters are defined as follows:

8 Databit 8 No parity N 1 Stopbit 1

RS232 Socket Assignment The following table details the pin assignments for the RS232 Sub-D 9 socket.

1

9

Function Pin No. Pin No. Function 9 N.C. CTS 8 7 RTS N.C. 6 5 COM (Gnd) N.C. 4 3 TxD RxD 2 1 N.C.

The connection between the computer and the test instrument is detailed below.

CTS

RTS

COM

TxD

RxD

CTS

RTS

COM

TxD

RxD

RS232 Socket onET Instrum

en t

RS2

32 S

ocke

t on

Use

rs P

C


9. IEEE 488.2 / RS232 Programming Format If your unit is fitted with a computer interface and you are unfamiliar with the method and conventions used in programming this section will prove helpful. Both IEEE488.2 and RS232 interfaces are similar in that the same programming terms are used. At least one RS232 port can be found on virtually all PC’s. Thus RS232 offers a cost-effective method of controlling simple test systems comprising of one or two units. IEEE 488.2 interfaces are ideal for building more complex test systems. Up to 30 different units can be controlled from one IEEE 488.2 card in your computer. An IEEE 488.2 or GPIB interface offers superior functionality and is the de facto standard for test system integrators.

Numerical Values All decimal values can be transmitted as whole numbers or integers. The following example shows how to set the current input to the electronic load.

Value to be Set Command Used

10A L,10A 2A L,2A

47A L,47A For more precise setting a value with up to four decimal places can be programmed. All the following command formats are valid and will be recognised by the unit. The values set must of course be within your instruments range.

Value to be Set Command Used 10A L,10.0A

1.25A L,1.25A 200mA L,0.2A 200mA L,.2A 500µA L,0.005

Use of Letters When using a numerical value you must initially tell the instrument what type of quantity you are setting. This is then followed by a comma then the numerical value and finally the engineering unit. The case in which the letters are written is of no significance. Commands can be written in lower, upper or mixed case.

For example: L,10A L,10a l,10a are all valid commands

Please note that for some instruments the engineering units and initial prefix do not change for different parameters. Instead the operating mode is altered.


Terminators and Delimiters Recognized command terminators are both the ASCII character or carriage return and the IEC-BUS statement EOI. These terminators are also used if your computer receives a message from the test instrument. A comma ( , ) is used as a delimiter between individual commands.

Changing the Range of a Parameter The ‘B’ symbol can be used to change the range of a given parameter to a value of the full output. It is mostly used to convert a range in to a percentage to help simplify setting and measurement. For example an Electronic Load ELP/SL 800/C50 has a maximum input current from the unit under test of 50A. If we wanted to turn this range in to a percentage and then set 50% (25A) and then 25% (12.5A) of the full output we would send the following commands: Step 1 Step 2 Step 3

L,25 Or L,25A

L,50 Or L,50A

L,B100 Or L,B100A

Please note that when you change the range you have the option tocontinue to use the engineering units (A) or to program without them.However your subsequent commands for that range must be writtenin the same form as the method chosen in step 1.

When changing the range it is also possible to change the engineering units used. Available engineering units are: ‘A’, ‘V’, ‘VA’, ‘W’ and ‘mA’ This can help clarify settings when the Electronic Load is fitted with the dynamic functions (/Dyn-B or /Dyn-LB). Thus if the constant voltage or constant power mode is chosen that range can be altered to include the ‘V’ or ‘W’ engineering unit instead of A. When the instrument is switched off the range setting is lost. Thus to set the output as a percentage step 1 will need to be followed each time the unit is switched off and then on again. The ‘B’ symbol can be used to alter the range for all control and measurement quantities except those that use Set (S) or Reset (R).


Command Sequence The order in which the commands are sent from the PC to the instrument is fixed as shown in the following example:

Value Name of quantity

L,B100,50

Range

Please note that if you are happy with the default range this part of the command can be omitted. If the output range is not changed then the engineering unit must always be included in the command.

Value

Engineering Unit Name of quantity

L,10A


10. Standard IEEE488.2/RS232 Interface Functions This section outlines the basic functions and operating modes that can be controlled and / or measured through your chosen computer interface. Other non-standard functions and operating modes are detailed in separate chapters in this manual.

Standby Function The standby function allows the input to the Electronic Load to be held or released. After sending your first BUS command the unit’s standby function is automatically activated. The input to the load is not released until the following command is sent:

Command Result

SB,R Releases Input to Electronic Load SB,S Activates the Standby Function (Input Held)

The previous or subsequently programmed values only become effective when the ‘SB,R’ command is used. The standby function must also be used to acknowledge errors. After removal of the error the unit is must be reset by sending the command ‘SB,S’. To release the input to the Electronic Load the command ‘SB,R’ must be used again.

Constant Current Mode

constant current mode by sending either of the commands ‘I,S’ or ‘R,R’. Similarly if the Electronic Load is fitted with dynamic options the constant power or constant resistance modes can be exited and the unit made to operate in constant current by using the commands ‘P,R’ or ‘U,R’

Constant current operation is the Electronic Load’s default mode. If you alter the operating mode to constant resistance operation then you can revert back to the unit’s

V

I

Command Result I,S Selects the Constant Current (CC) Operating Mode R,R Exits Constant Resistance Mode. Unit reverts to CC Mode. P,R Exits Constant Power Mode. Unit reverts to CC Mode. U,R Exits Constant Voltage Mode. Unit reverts to CC Mode.

* Please note that ‘P,R’ and ‘U,R’ commands are only valid when the Load is fitted with the dynamic option (/Dyn-L or /Dyn-LB)


Setting the Load Current The command to set the load current is sent by firstly identifying the quantity you are setting ‘L’. This is then followed by a comma, ‘ ,’ then the numerical value ‘xx’ and finally the engineering unit ‘A’. For example, the command ‘L,2A’ sets the load current drawn by from the unit under test to 2A.

Command Result L,xxA Sets the Load Current to the Desired Value*

*where ‘xx’ equals the desired load current value

Constant Resistance Mode

operate in constant resistance mode. The command R,S is used to select the constant resistance mode. If the command R,R is sent over the BUS then the constant resistance mode is exited and the constant current mode of operation automatically selected.

Besides constant current operation all Electronic Load’s manufactured by ET can

V

I

Command Result R,S Unit Enters Constant Resistance Mode R,R Exits Constant Resistance Mode. Unit reverts to CC Mode


Setting the Resistance Value Before setting the resistance level a series of calculations needs to be made. The following diagram shows the equations needed and an example based on an ELP/SL 401/C30/LT (VMAX =100V) where a constant resistance of 10Ω needs to be set.

L,1A Format = L,xxA Where xx is the CR value to be set

Step 3 Programme the resistance

value (10Ω in example)

10V 10 = 1

xx =

100 10 = 10V

K =

xx =

K R

Step 2 Calculate the Programming

value (xx)

K =

VMAX 10

Step 1 Calculate the constant (K)

So in the example given the command ‘L,1A’ will simulate a constant resistance of 10Ω at the unit under test’s output. Depending on the actual voltage available from the unit under test the load current will be automatically altered to maintain the constant resistance value that has been set.

Command Result R,S Unit Enters Constant Resistance Mode

L,xxA Sets the CR value where xx is the desired resistance value Ensure the Electronic Load is operating in its constant resistance mode

before setting the resistance value. Failure to do this will mean your intended constant resistance will in fact be a constant current.


Measuring Functions If your unit is fitted with listener capabilities then it is possible to read the voltage and current from the unit under test at the Electronic Load’s input.

Status Enquiry The ‘status’ command is used to see the maximum value for a given range and your last programmed or measured value.

Unit Version Enquiry The ‘ID’ command is used to interrogate the unit as to its version and part number. A message similar to that shown below will be displayed on your computer monitor:

EUROTEST V1.19 ELP/SL 400/C20

Command Result MV Measures the Voltage into the Electronic Load MC Measures the Current into the Electronic Load

Command Result STATUS,L Reads Back the Maximum Current Value and the Last Set Value

STATUS,MC Reads Back the Maximum Current and the Last Current Measurement

STATUS,MV Reads Back the Maximum Voltage and the Last Voltage Measurement

Command Result ID Unit responds with version and part number

Please note that the ‘Status’ command reads back the value produced from the last measurement or setting command not necessarily what is present at the Load’s input. The ‘MV’ or ‘MC’ commands must be used to ascertain the present voltage or current inputs to the Electronic Load

IEEE 488.2 / RS232 Card Unit’s Part Number Revision Number


DI Function The ‘DI’ command can be implemented to see which mode the unit is operating in and to ascertain whether there is an error being signalled.

The 16-bit feedback message indicates the following states: Description Bit Number

0 1 2 3 to 15

Command Result DI Unit responds with operating mode and fault status and part number

Error…………………………………………………………0…………………………….. No Error……………………………………………………..1…………………………….. Constant Resistance Mode………………………………………….0……………………... Constant Current Mode……………………………………………..1……………………... Constant Current Mode…………………………………………………….. 0……………... Constant Resistance Mode…………………………………………………. 1……………...

Bits 3 to 15 have not been assigned


Error Messages If the unit receives an error message an error message an SRQ will be requested. The status byte has the following assignments:

Function Status Byte Meaning D108 0 Not extended D107 1 Unit requests SRQ D106 0 Normal D105 0 Ready D104 – D101 0001 Syntax Error 0010 Command Error 0011 Range Error 0100 Unit Error 0101 Hardware Error 0110 Read Error

Syntax Error The sequence of parameters has not been maintained, or, an

incorrect command character was detected. Command Error The unit does not recognize the command used. Range Error The output value is higher than the range currently set. Unit Error The unit does not conform to the unit currently set, or, the unit of

range and the unit of set point value are not the same. Hardware Error A malfunction has been detected in the hardware. Read Error Read string.


11. Dynamic Functions If specified on order your unit will be fitted with the dynamic option. The dynamic option allows constant voltage & constant power loading as well as the standard constant current & constant resistance modes of operation. In addition, the dynamic option permits the current rise time to be varied. During constant current operation the built in generators allow the user to choose between a square, triangular and sine wave. The pulse width modulation can be adjusted from 10% to 90% and the frequency can be varied from 0.1Hz to 2000Hz. If you are unsure whether your Electronic Load is fitted with dynamic functions please refer to the type label on the unit and the following table for an explanation.

Option Code Description /DYN-L Dynamic functions operable via the front panel only /DYN-B Dynamic functions operable via IEEE and/or RS232 interfaces only /DYN-LB Dynamic functions operable via front panel controls and by BUS

Selecting Dynamic Operation If you wish to operate the dynamic functions from the front panel then simply press the ‘DYN’ button so that the ‘DYN LED’ becomes lit. Pressing the ‘DYN’ button once more will cause the Electronic Load to exit its dynamic mode. If you want to enter or exit the dynamic functions by the IEEE488.2 / RS232 interface then the following commands are used: Command Result

DY,S Unit Enters Constant Current Dynamic Mode DY,R Exits Dynamic Mode. Unit reverts to Normal CC Mode

I,S Exits Dynamic Mode. Unit reverts to Normal CC Mode

When the dynamic mode is activated as detailed above the default operating mode is constant current.


Constant Voltage Operation

cause the unit to revert to its previous operating mode. If using the computer interface then the command ‘U,S’ must be sent over the BUS to operate in constant voltage mode. If the command ‘U,R’ is sent over the BUS then the constant voltage mode is exited and the constant current mode of operation automatically selected.

If you are using the front panel controls simply depress the ‘CV’ button ensuring that the ‘CV LED’ is lit. Pressing the button again will exit constant voltage operation and

V

I

To set the constant voltage level on the front panel the current potentiometer is used. However for both front panel and computer control the following calculation will need to be made to ascertain the current value needed to set your desired constant voltage level. You will again need to know the maximum current and voltage ranges of your Electronic Load. Please refer to your part number and the table in section 1 if you are unsure of your unit’s range.

X = V * IMAX VMAX

Where; X = The current value needed for a given constant voltage V = The desired constant voltage level

VMax = Unit’s maximum permissible voltage IMax = Unit’s maximum permissible current

Example: ELP/SL 804/C50. In this instance; VMAX = 400V and IMAX = 50A

Desired constant voltage = 40V

Step 1 Step 2 Step 3

∴ X = 4 X = 40 * 50 400

V * IMAX VMAX

X

If using front panel controls set the unit to CV mode ensuring the ‘CV LED’ is illuminated. Now turn the current potentiometer until 4A is displayed. The preset function can be used to give an almost instantaneous constant voltage of 10V.

Command Result U,S Unit Enters Constant Voltage Dynamic Mode L,4A Sets a Constant Voltage of 10V (for example given) U,R Exits Constant Voltage Mode. Unit reverts to Normal CC Mode


Constant Power Mode

controls on your electronic load then the ‘CP’ button can be pressed. If you are using the computer interface then the command ‘P,S’ is used to enter the constant power mode. If the command ‘P,R’ is sent over the BUS then the constant power mode is exited. The unit will automatically revert to its constant current mode of operation.

To operate your unit as a constant power load you must first enter the dynamic mode by the front panel or through the computer interface. If you are using the front panel V

I

The value used to achieve your desired constant power is calculated as follows Where; X = The current value needed for a given constant power P = The desired constant power level

PMax = Unit’s maximum permissible power IMax = Unit’s maximum permissible current

Example: ELP/SL 200/C10. In this instance; PMAX = 200W and IMAX = 10A Desired constant power = 25W Step 1 Step 2 Step 3 If using front panel controls ensure that the ‘CP LED’ is lit and turn the current potentiometer until a value of 1.25A is displayed. Remember you can use the preset function to set your desired constant power value. The following computer commands are used to set the constant power of 25W given in the example.

Command Result P,S Unit Enters Constant Power Dynamic Mode

L,1.25A Sets a Constant Power of 25W (for example given) P,R Exits Constant Power Mode. Unit reverts to Normal CC Mode

∴ X = 1.25 X = 25 * 10 200

P * IMAX PMAX

X =

X = P * IMAX PMAX


Dynamic Waveforms Another advantage of the dynamic option is that the waveform can be selected between square, triangular and sine. The frequency can be adjusted between 0.1-2000Hz by using the potentiometer on the front panel or by sending a command over the computer interface.

Square Wave The square wave is the default waveform selected by your Electronic Load once the dynamic mode has been initiated.

DC Current

Dynamic Current Amplitude

Time

If using front panel controls the procedure for selecting the square wave and setting the DC and dynamic current along with the frequency is outlined below:

Ensure that the unit is in its dynamic mode –‘Dyn Mode’ LED is lit If ‘Dyn Mode’ LED not lit then operate ‘Dyn’ switch Ensure that the square wave is selected – LED lit If LED not lit press the square wave button

Use the Current potentiometer to set the DC load current The DC current can be read from the ‘A’ Display during adjustment

Use the dynamic potentiometer to set the dynamic peak current The dynamic current can be read from the ‘A’ Display

Use the frequency potentiometer to set the desired frequency A frequency value between 0.1-2000Hz is selectable and can be read

from the ‘V’ display

Please note that the maximum dynamic current will be the maximum current rating of the unit.


Programming a Square Wave Once the dynamic mode has been entered by the computer interface the Electronic Load will automatically select the square wave. If another waveform has been selected then the square wave can be re-entered by using the ‘RE,S’ command. As with front panel operation the computer can be used to adjust the DC or minimum current, the dynamic peak current and the frequency. The following table details the relevant commands for setting and adjusting the Load’s square wave function.

*where ‘xx’ equals the value to be set

Pulse Width Adjustment Another useful feature is that the pulse width ratio can be adjusted between 10 – 90% If using the front panel controls the pulse width of the square wave is adjusted by using the potentiometer provided. The computer command for varying the pulse width is ‘IP’ followed by coma ‘ , ’ and then the desired width of the pulse.

Command Result RE,S Unit Enters Square (Rectangular) Wave Operation L,xxA Sets the Minimum Current to the Desired Value*

LD,xxA Sets the Dynamic Peak Current to the Desired Value* FRQ,xxHz Sets the Frequency of the Square Wave to the Desired Value*

PWA = 90%

Amplitude

Time

PWA = 50%

Amplitude

Time

50%

100%

90%

100%

Command Result IP,xx Sets the Pulse Width*

*where ‘xx’ equals the pulse width value to be set between 10% and 90%

Please note that the pulse width can only be varied if the square wave is selected. This function will not work for the triangular or sine waves.


Triangular Wave If a triangular or sawtooth waveform is required the Electronic Load must be operating in its dynamic mode.

Am

plitude

Time

DC Current

Dynamic Current

The following procedure should be followed if the triangular wave and frequency is to be set from the front panel controls.

Ensure that the unit is in its dynamic mode –‘Dyn Mode’ LED is lit If ‘Dyn Mode’ LED not lit then operate ‘Dyn’ switch Select the triangular wave by pressing the switch – LED lit If LED not lit press the triangular wave button again







Programming a Triangular Wave Once the dynamic mode has been entered by the computer interface the Electronic Load will automatically select the square wave. To select triangular wave loading the ‘DR,S’ command is used. As with front panel operation the computer can be used to adjust the DC or minimum current, the dynamic peak current and the frequency. The following table shows the relevant commands for setting and adjusting the Load’s triangular wave function.

Command Result DR,S Unit Enters Triangular (Sawtooth) Wave Operation L,xxA Sets the Minimum Current to the Desired Value*

LD,xxA Sets the Dynamic Peak Current to the Desired Value* FRQ,xxHz Sets the Frequency of the Triangular Wave to the Desired Value*

DR,R Unit exits Triangular Wave and Enters Default Square Wave Operation



Sinewave To select sinewave operation the Electronic Load must be functioning in its dynamic mode.

DC Current

Dynamic Current Amplitude

Time

As with the square and triangular waves the sinewave can be chosen and adjusted by using front panel

Ensure that the unit is in its dynamic mode –‘Dyn Mode’ LED is lit If ‘Dyn Mode’ LED not lit then operate ‘Dyn’ switch Ensure that the sinewave is selected – LED lit If LED not lit press the sinewave button







Programming a Sinewave Once the dynamic mode has been entered by the computer interface the Electronic Load will automatically select the square wave. To select the sinewave the ‘SI,S’ command is used. As with front panel operation the computer can be used to adjust the DC or minimum current, the dynamic peak current and the frequency. The following table shows the relevant commands for setting and adjusting the Load’s triangular wave function.


Current Rise Time Adjustment Where your Electronic Load is fitted with the dynamic option a further feature is the ability to adjust the rise time of the dynamic current. A potentiometer on the front panel allows the rise time to be increased in seven steps. The current rise time can be varied for square, triangular and sinewave operation. This function can also be set by the computer interface. The following table shows the commands used.

Command Result SI,S Unit Enters Sinewave Operation

L,xxA Sets the Minimum Current to the Desired Value* LD,xxA Sets the Dynamic Peak Current to the Desired Value*

FRQ,xxHz Sets the Frequency of the Sinewave to the Desired Value* SI,R Unit Exits Sinewave and Enters Default Square Wave Operation

Command Result CRT1,S Rise Time of the Dynamic Current Increased by one step CRT1,R Resets the Current Rise Time CRT2,S Rise Time of the Dynamic Current Increased by two steps CRT2,R Resets the Current Rise Time CRT3,R Rise Time of the Dynamic Current Increased by three steps CRT3,S Resets the Current Rise Time CRT4,R Rise Time of the Dynamic Current Increased by four steps CRT4,S Resets the Current Rise Time CRT5,R Rise Time of the Dynamic Current Increased by five steps CRT5,S Resets the Current Rise Time CRT6,R Rise Time of the Dynamic Current Increased by six steps CRT6,S Resets the Current Rise Time CRT7,R Rise Time of the Dynamic Current Increased by seven steps CRT7,S Resets the Current Rise Time

The maximum rise time available is

12. Other Options Available This section details the other non-standard functions that may be fitted to your Electronic Load. If you are unsure whether the unit your using has the capabilities outlined in this section please check the unit’s part number on the type label and the explanation in the table below.

Option Code Description /OV Built in power supply to run full load from 0Vdc /OR Built in power relay for real short circuit

Built in PSU (Option /OV) If this option was specified on order your Electronic Load will have been built with an internal power supply. This allows the Load to operate from zero volts to the maximum by simulating a short circuit. The following sketch shows the internal configuration of the Electronic Load if this option is fitted.

Internal Power Supply

+

-

Load

GND +V - Sense -

+ + Sense

This option is useful when batteries and capacitors need to be fully discharged. Another application for units fitted with this option is to test the current limit on power supplies.


Built in Power Relay (Option /OR) If your unit is fitted with this option than a power relay has been fitted between the positive and negative input of the Electronic Load. The sketch below shows internal configuration of the Electronic Load when built with the relay.

+

-

Load

- Sense -

+ + Sense

Power Relay

A button will be fitted to the front panel to switch the relay in and out. If your Electronic Load has also been fitted with a computer interface then the following terms can be used to change the position of the relay. Command Result

OR,S Sets Power Relay to IN or ON OR,R Resets Power Relay to OUT or OFF

This option is useful in such applications as short circuit testing of power supplies.

Please note that you will not be able measure below 1V with this option. For current limit testing and to be sure that batteries and capacitors are fully discharged the /OV option is recommended.


13. Commands for IEEE488.2 and RS232 The following table provides a quick reference for the control and measurement commands used for your unit. For a further explanation of the commands given on this page please refer to the relevant sections in this manual.

Function Command Result Setting L,xxA Sets the load current to the desired value. Standby SB,R Releases input to electronic load. Standby SB,S Activates the standby function (input held). CC Mode I,S Selects the constant current (cc) operating mode. CC Mode I,R Exits any other operating mode. Unit reverts to cc mode. CR Mode R,S Unit enters constant resistance mode. CR Mode R,R Exits constant resistance mode. Unit reverts to cc mode. CP Mode* P,S Units enters constant power mode. CP Mode* P,R Exits constant power mode. Unit reverts to cc mode. CV Mode* U,S Unit enters constant voltage mode. CV Mode* U,R Exits constant voltage mode. Unit reverts to cc mode. Dynamic* DY,S Unit enters constant current dynamic mode. Dynamic* DY,R Exits dynamic mode. Unit reverts to normal CC mode. Dynamic* LD,xxA Sets the dynamic peak current to the desired value. Square wave* RE,S Unit Enters square wave Operation. Square wave* RE,R Unit exits other waveform operation and reverts to square wave. Square wave* IP,xx Sets the pulse width value. xx = 10 for 10%, 50 for 50% etc Triangular wave* DR,S Unit enters triangular wave operation. Triangular wave* DR,R Unit exits triangular wave and reverts to square wave operation. Sinewave* SI,S Unit enters sinewave operation. Sinewave* SI,R Unit exits sinewave and reverts to square wave operation. Frequency* FRQ,xxHz Sets the frequency of the waveform to the desired value. Rise Time* CRTxx,S Rise time of the dynamic current is increased. xx = 1-7 steps . Rise Time* CRTxx,R Resets the Current Rise Time. xx = 1-7 steps. Power Relay** OR,S Sets Power Relay to IN or ON. Power Relay** OR,R Resets Power Relay to OUT or OFF. Unit Identity ID Unit responds with version and part number. Unit Status DI Reads back the operating mode and fault status. Measurement MV Measures the voltage into the electronic load. Measurement MC Measures the current into the electronic load. Measurement STATUS,L Reads back the maximum current value and the last set value. Measurement STATUS,MC Reads back the max current and the last current measurement. Measurement STATUS,MV Reads back the max voltage and the last voltage measurement.

* These commands are only valid when the unit is fitted with the dynamic option ** These commands are only valid when the unit is fitted with a power relay, option /OR


14. Technical Data With the unit‘s linearly controlled MOS end stage, extremely high current rise times and an outstanding current stability are achieved. Mains connection 115 VAC, 230 VAC -10%, +15%, Mains Frequency 50 Hz / 60Hz Isolation 3750 VAC Increase of current Typically 2 µs / A Standard Operating modes constant current constant resistance Additional Dynamic Modes constant voltage constant power Minimum resistance setting dependent on max. current Temperature coefficient 25 ppm / °C Operating temperature 0 - 50 °C Warm-up time 5 mins Analogue interface, all functions 0-5 VDC, TTL on SUB-D 25


15. Control Panel View

ET System electronic GmbH Made in Germany

A

ERROR

Ω

V

LOCAL

ERROR

TALK

LISTEN

REMOTE

IEEE 488

Ω-SET I-Preset I-/R- MODE STAND-BY

CURRENT

R-MODE STBY I -MODE

O

POWER

ELECTRONIC LOAD ELP/SLM

- + I N P U T


16. Rear Panel View

230V

O N

D I

P 1

23

45

67

8

Address

RS 232

IEEE 488

-S

- + +S


17. Service and Support In the first instance please contact your local distributor if your ET instrument requires service or support. Alternatively you can contact one of the ET group companies as detailed below.

ET System electronic GmbH

ET- G

erm

any Postfach 80

Hauptstraβe 119-121 D-68804 Altluβheim Deutchland T/P: ++49 (0) 6205 39480 Fax: ++49 (0) 6205 37560 Web: www.ETSGmbH.de Email: [email protected]

ET Power Systems Ltd

ET- U

K Top Riley Eyam, Hope Valley

S32 5QZ U.K. T/P: ++44 (0) 1433 639343 Fax: ++44 (0) 1433 639073 Web: www.etps.co.uk Email: [email protected]

ET- F

ranc

e

ET System electronic 4 rue Ampere F-38080 L’Isle d’Abeau France T/P: ++33 (0) 4 74 27 82 34 Fax: ++33 (0) 4 74 27 80 68 Web: www.et-systeme.com Email: [email protected]

ET offers a calibration service and out of warranty repairs for ET Test and Measurement Instruments. Please contact your distributor or nearest ET Company for further details.


About this ManualScope of ManualOptions Available

Goods Inwards InspectionVisual Inspection

InstallationMains OperationMains Socket and Fuse

Power TerminalsInput SocketsBack Panel Input Terminals

Sense ModeFront Panel OperationInitial Start UpCurrent PresettingCurrent SettingResistance PresettingResistance SettingCalculating RMIN

Analogue InterfaceSUB-D 25 Pin AssignmentTypes of Analogue InterfaceSetting the Operating ModeSetting the Load CurrentSetting the Load ResistanceOperating the Standby FunctionVoltage MonitorCurrent MonitorFault SignalConstant Current SignalConstant Resistance SignalStandby Function Signal

IEEE 488.2 / RS232 Interface SetupSelecting the System Operating ModeSetting the 8-Way DIP Switch (IEEE 488.2 Operation)IEEE 488.2 Permissible AddressesIEEE488.2 BUS CapabilitiesIEEE 488.2 Socket AssignmentSetting the 8-Way DIP Switch (RS232 Operation)RS232 Socket Assignment

IEEE 488.2 / RS232 Programming FormatNumerical ValuesUse of LettersTerminators and DelimitersChanging the Range of a ParameterCommand Sequence

Standard IEEE488.2/RS232 Interface FunctionsStandby FunctionConstant Current ModeSetting the Load CurrentConstant Resistance ModeSetting the Resistance ValueMeasuring FunctionsStatus EnquiryUnit Version EnquiryDI FunctionError Messages

Dynamic FunctionsSelecting Dynamic OperationConstant Voltage OperationConstant Power ModeDynamic WaveformsSquare WaveProgramming a Square WavePulse Width AdjustmentTriangular WaveProgramming a Triangular WaveSinewaveProgramming a SinewaveCurrent Rise Time Adjustment

Other Options AvailableBuilt in PSU (Option /OV)Built in Power Relay (Option /OR)

Commands for IEEE488.2 and RS232Technical DataControl Panel ViewRear Panel ViewService and Support

electronic load elp/slm - et system...elp/slm 100/400/cxx 10000 1-400 doc: elp/slm/1002 page 4 of 48...

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