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SPiiPlus Training Class

Safety and Faults

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Faults Mechanism

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All fault responses can be customized by the user

• Fault: An abnormal situation detected by the controller related to safety of motion, hardware damage, faulty wiring, EtherCAT errors, limit switch tripped, etc.

• Faults and errors are monitored every controller cycle.

• The controller has a predefined set of faults and default responses.

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Faults Mechanism

• Example faults:o Encoder error due to bad wiringo Drive alarm caused by problem with the power amplifiero Axis limit switch trippedo E-Stop activationo Critical position error caused by a driving axis into a hard

stop

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Some Predefined Axis and System Faults

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Axis FaultsRight Limit

Left Limit

Soft Right Limit

Soft Left Limit

Encoder not connected

Encoder error

Drive Alarm

Position Error

Critical Position Error

Velocity Limit

Overcurrent

System FaultsProgram error

Memory overuse

Runtime overload

Servo Processor alarm

Servo Interrupt

Emergency stop

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Axis Fault Variables

• FAULTo Encodes all faults for a certain axis. For example, ON

FAULT(1).#ENCNC will activate an autoroutine when axis 1 encoder is disconnected.

• FMASKo Masks a defined axis fault. For example, FMASK(0).#RL=0

will mask axis 0 hardware right limit fault.

• FDEFo Activates/deactivates default response to axis fault. For

example, FDEF(3).#SLL=0 will disable the default response to axis 3 software left limit fault.

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System Fault Variables

• S_FAULTo Aggregates one specific fault for all axes. For example, ON

S_FAULT.#LL will activate an autoroutine when any axis passes the left limit.

• S_FMASKo Masks a defined system fault. For example,

S_FMASK.#ES=0 will mask the Emergency Stop fault.

• S_FDEFo Activates/deactivates default response to system fault. For

example, S_FDEF.#ES=0 will disable the default response to the Emergency Stop fault.

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Customized Fault Responses

• The user can define a customized fault response that can override/supplement the default fault response by:o Activating the fault FMASK variableo Writing an autoroutine, for example:

! Axis 0 critical position error is being checkedFMASK(0).#CPE = 1FDEF(0).#CPE = 0

STOP

ON FAULT(0).#CPE; BLOCK ! Run on critical position error KILL (0,4) ! Kill axis 0 and 4 START 3, User_PE ! Run buffer 3 starting at label User_PE DISP "Critical position error Axis 0"END; RET

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Safety and Faults Configurator

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• MMI component used for configuration of controller responses to faults

Red LED indicates a

fault

Allow default

fault response

Allow detection

of fault

Invert fault signal (if necessary)

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Safety and Faults Monitor

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• Provides immediate monitoring of axis and systemfaults

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Default Responses

• The controller provides default responses for most faults

• A default response can be one of the following:o No response – for indication only.o Kill motion – when the axis is under controlo Disable motor – when the controller can’t control the axiso Kill Disable – Kill motion followed by disable

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Default Responses

• To view default responses:o In the System Information Viewer, look under “Safety &

Fault Response” heading to view predefined fault responses per axis

o Alternatively, the terminal command #SC prints the same information to the Communication Terminal

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Fault Mechanism

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Fault signal

Fault input state: 0=Off, 1=On

Fault status: 0=not active, 1=active

FAULT

Fault mask:0=masked, 1=not masked

Logic inversion: 0=not inverted, 1=inverted

- Read only variables

Default fault response: 0=not active, 1=active

FDEF

Response

- Read/write variables

[and]

[and]

[inversion]

FMASK

SAFINI

SAFIN

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Fault Mechanism

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Example 1 – Axis 0 left limit faultAxis 0 left limit

input is on

Fault input state is on

Fault statusis active

Fault is notmasked

Logic inversionnot applied

Default faultresponse is active

Kill Motion

[and]

[and]

[inversion]SAFINI(0).#LL = 0

SAFIN(0).#LL = 1

FMASK(0).#LL = 1

FAULT(0).#LL = 1

FDEF(0).#LL = 1

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Fault Mechanism

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Axis 0 left limit input is on

Fault input state is on

Fault statusis not active

Fault is notmasked

Logic inversionis applied

Default faultresponse is active

No response

[and]

[and]

[inversion]SAFINI(0).#LL = 1

SAFIN(0).#LL = 1

FMASK(0).#LL = 1

FAULT(0).#LL = 0

FDEF(0).#LL = 1

Example 2 – Axis 0 left limit fault

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Encoder Faults

• Encoder Not Connectedo Quadrature encoders:

Checked by HW to verify continuity between A/A’ and B/B’ on quadrature encoders

o Analog Sin-Cos encoders: Checked by SW using Sin^2 + Cos^2

• Encoder Erroro Checks encoder logic by the SW (Firmware) to verify legal transfers

between A and B signals (00 <=> 01 <=> 11 <=> 10)

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Fault Quad Encoder Sin-cos EncoderEncoder not connected

Encoder Error

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Hardware Limit Faults

• During operation, when the left limit switch is on, the controller detects a left (negative) limit fault.

• During operation when the right limit switch is on, the controller detects a right (positive) limit fault.

• As a default response, the controller kills the violating motor.

• As long as the fault is active, the controller kills any motion toward the limit while motion away from the limit is allowed.

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Software Limit Faults

• The user can define left and right software limits in the Adjuster Wizard:

• Unlike hardware limits, the software limit causes the fault before the trajectory passes the software limit position

• The controller provides processing so the termination point is very close to software limit – using the KDEC deceleration variable

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• As long as the fault is active, the controller kills any motion toward the limit while motion away from the limit is allowed

Softwareleft limitposition

Software right limit position

Motion range

Axis decelerates towards the software

limit position

Axis velocity = 0

Left limit switch

Right limitswitch

Software Limit Faults

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Velocity and Acceleration Limits

• Maximum reference (not feedback) velocity (XVEL) and acceleration (XACC) can be specified for each axis.

• Calculated automatically by the Adjuster Wizard based on motor data entered earlier in the Adjuster process

• Can be specified by user if necessary

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Important – the velocity limit (XVEL) parameter affects the servo control loops because it scales velocity feedback. Make sure XVEL is set properly before tuning.

Velocity and Acceleration Limits

• When the commanded motion exceeds the maximum velocity value, a FAULT.#VL fault is generated.

• When the commanded motion exceeds the maximum acceleration value, a FAULT.#AL fault is generated.

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Current/Torque Protection

• There are three current/torque protection variables defined in terms of percentage of peak drive current:o XRMS – defines maximum allowable RMS current. If

violated, an overcurrent fault occurs.o XCURI – defines absolute maximum current when axis is

idle. This sets a physical limit on drive output.o XCURV – defines absolute maximum current when axis is in

motion. This sets a physical limit on drive output.

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Current/Torque Protection

• Overcurrent protectiono The controller provides over-current protection by

calculating RMS currento The protection relates to continuous current rating of drive

and motoro The Adjuster Wizard automatically calculates current

protection parameters based on motor and drive data entered earlier in the Adjuster process

o Current protection parameters can be modified by users if necessary

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Current/Torque Protection

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Position Error Faults

• There are six variables for position error faults

• As a default response,the critical positionerror fault disables thedrive

• The position error faulthas no defaultresponse (indicationonly). The user candefine a customizedresponse.

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Error Mechanism

• A four-digit error code is generated after any malfunction during operation.

• The controller returns error codes which belong to the following categories:o ACSPL+ Syntax Errors: numbers 1000 to 1999o ASCPL+ Compilation Errors: 2000 to 2999o ACSPL+ Runtime Errors: 3000 to 3999o Motion Termination Errors: 5000 to 5150o System Errors: 5151 to 5999o EtherCAT Errors: 6000 to 6999o Reserved for user-defined error codes: 9000 and above

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• The meaning of an error code can be determined byo Looking up the error code in section 5 of the ACSPL+ Command and

Variable Reference Guide

o Querying the error code in the Communication Terminal using double question mark syntax For example; ??5167 returns “Initialization problem: Number of

drive modules does not meet the configuration”

• If an error occurs when using the MMI, a pop up window displays the error code along with its meaning.

Error Mechanism

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Error Mechanism

• MERR is an ACSPL+ standard variable that stores motion termination cause per axis

• If axis motion terminates without error, MERR returns 0

• If axis motion terminates with error, MERR returns the corresponding 4-digit error code in the range of 5000-5150

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Error Mechanism

• PERR is an ACSPL+ standard variable that stores ACSPL+ error code (progam error) per program buffer

• If an ACSPL+ error occurs during program execution, the controller stores the error code in the corresponding element of the PERR array

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Error Mechanism

• In addition to the SPiiPlus error codes, the user can add their own codes in the range of 9000 and above. For example:

ON (RPOS(axis) > 10000) ! Condition for error KILL (axis), 9123 ! Kill motion citing error code 9123 DISP "Cause of motion termination", MERR(axis); FCLEAR(axis)! Reset MERR flag of the axisRET

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EtherCAT Diagnostics

• EtherCAT diagnostic commands allow you to view connected EtherCAT network nodes, operational state, network offsets (variables), errors, etc.o There are three diagnostic commands:o #ETHERCAT – A terminal command showing connected EtherCAT

nodes, corresponding states, and variable offsetso ECST – Shows the status of the EtherCAT network. All bits should be on

with the possible exception of bit 4 (synchronization bit) if using 3rd party IO.

o ECERR – Gives an error code that can be sent to ACS Support for troubleshooting purposes. If zero, no errors exist

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Example 1

• A vision system moves a scanner head along a single linear axis

• Safety and faults need to be configured for the axis

• If the scanner head moves into the limit, it is important not to remain there due to hazards

• Turn off the default response to limits for the axis and define new response so the scanner head does not stay in the limit

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Example 1

• Load Safety and Faults example 1 to an empty buffer, review code, and execute.o If using trainer unit, command motion and manually toggle

limit switcheso If using simulator, command motion and simulate limit

switches by toggling. SAFINI(X).#LL, or SAFINI(X).#RL

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Example 2

• The vision system needs to wait for a signal from the user before it is allowed to continue operation

• Modify example 1 so that after moving out of a limit, code execution halts until user sends a signal from the terminal (i.e. user changes the state of a global variable from the terminal)

• Use the terminal to notify the user of any safety issues (use DISP to display messages to the Terminal), and prompt for user input when necessary

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Example 3

• For safety purposes it is desired to disable all axes and stop the program if the user does not send a signal for an extended amount of time

• Modify example 2 accordingly, define an appropriate user-response timeout length

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