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Using RSLinx OPC ServerPublish Date: Jan 28, 2009

OverviewThe National Instruments Industrial Automation Servers CD has an Allen Bradley (RSLinx) driver that can communicate with RSLinx through a dynamic link library (DLL). With the release ofIndustrial Automation Server CD 1.1, this server became an OPC server. Any OPC client, such as Lookout, BridgeVIEW, or other packages on the market, can connect to this server. RockwellAutomation developed their own OPC Server in version 2.0 of RSLinx. This version has been upgraded to version 2.20.Rockwell Automation RSLinx 2.10 is an OPC server, meaning that any OPC Client should be able to exchange data with this server. The OPC server is available only with the OEM version or thefull version, so the lite version of RSLinx does not have the OPC Server included. RSLinx OPC server is an in-process type of server, which means that you have to load a DLL to communicatewith it. RSLinx 2.0 to 2.20 OPC servers only support the browsing capability on Control Logix 5000 series PLCs. Other Allen Bradley PLCs can be used on the OPC server by manually adding theaddresses to be seen.

Another mechanism of communication between applications and RSLinx is through the DDE server that comes with RSLinx. The DDE server is only available for Rockwell Automation DDE clientsin the OEM version. The drawback of DDE connection is that it is slower than OPC. If you decide to use the LabVIEW DDE VIs, then you need to have the full version of RSLinx.

This document was created using RSLinx 2.20.01.107.01, Allen Bradley MicroLogix 1500 PLC, ServerExplorer 2.4.1, Lookout 4.5 and the LabVIEW DSC module 6.0.2.. The cable model numberused was 1761-CBL-PM02.

Table of ContentsConfiguring an Allen Bradley PLC in RSLinx

Connecting ServerExplorer to RSLinx

Connecting Lookout to RSLinx

Connecting LabVIEW to RSLinx

Connecting the LabVIEW DSC Module to RSLinx

1. Configuring an Allen Bradley PLC in RSLinx1. Start and click on RS Linx Communications>>Configure Drivers.

2. The dialog box appears. Click on the pull-down menu and choose your communication driver from the list. For instance, if you have the regular serialConfigure Drivers Available Driver Typesconnection, choose from the list.RS-232 DF1 devices

3. Click Add New.

4. Enter any name you want for the driver name in the dialog box. Click when you are done.Add New RSLinx Driver OK

5. Configure the device. Click the button and RSLinx will auto-configure the device for you. If the auto-configure failed, contact Allen Bradley technical support for help. Click Auto-Configure Helpif you need more information about device configuration. Click to go to the next step.OK

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6. Now you should be able to see the driver that you just created in the section of the dialog box. Make sure there is no error showing and that the Configured Drivers Configure Drivers Statusindicates . Click .Running Close

Now you should be able to see your device when browsing the tree.

7. If you do not see your PLC in the list, uncheck the checkbox and click . When you highlight the items in the window, you should see the little squares in the communicationAutobrowse Refreshicon blinking, meaning that there is a communication link between the PC and the PLC.

8. Right-click your PLC icon and click .Configure New DDE/OPC Topic

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9. A new access path is added for your server, so when you define the access path in your SCADA software, you have to use the following syntax: [Access Path]Item. You can enter any name youwant for the access path. In this example the access path is ML1500.

10. Click after you are finished, and click when prompts you to update the topic.Done Yes RS Linx

Now you should be able to access all the available registers on your PLC from any OPC client software. With the access path ML1500, the syntax to access the register N7:0 would be[ML1500]N7:0. Next, test the OPC server just created using .RS OPC Test Client

10. Launch the OPC Test Client from . Then select .Start>>Programs>>Rockwell Software>>OPC Tools>>OPC Test Client File>>New

11. Select and click .RSLinx OPC Server OK

12. At this point you should see a blank screen called . Select .OPC Test Client – [~RSLinx OPC Server] Group>>Add Group

13. Enter anything for the group name.

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14. Click . Now you should be able to see the group in the previous window.OK

15. Select .Item>>Add Item

16. For the access path, enter the topic name you defined previously and type the register name you are trying to get data from or writing to. Click the button and the item name shouldAdd Itemappear in the left-most field, as shown in the illustration. Add all the items you want, and click when you are done.OK

You should see the items and value that you just connect to under .ItemID

2. Connecting ServerExplorer to RSLinx

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1. Launch the Industrial Automation Server Explorer 1.1 (or higher). Right-click on and choose .RSLinx OPC Server Wizard

2. It is important to choose the In-proc Server (DLL). RSLinx does not support a Local Server. Click to connect to the server.Next

3. Define the group name and the update rate. Click then at the next screen.Next Finish

4. At this point you should be able to see the green traffic light meaning that ServerExplorer has successfully connected to the OPC server. Create an item by right-clicking on the group name thatyou just created, then click .Add/Edit Items

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5. The can be any string. The should be in the [Access Path]Item format. In this example it should be . Then click .Name (Device\Item) Item ID [ML1500]O0:0 Add

If you are using RSLinx 2.20.01 or a later version/build and a Control Logix 5000 Series PLC, you should be able to browse and select the registers. However, for all other Allen BradleyNote:PLCs, RSLinx OPC Server does not support browsing, and you will have to manually enter the and .Device Name Item ID

6. all items.Validate

7. Click , and you should be able to see register data in ServerExplorer.OK

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3. Connecting Lookout to RSLinxLookout can connect to the RSLinx OPC server through the OPCClient object. This document assumes that you know Lookout. If you do not have any previous experience with Lookout, then westrongly recommend you to go through the introductory material in the Lookout documentation.

Lookout currently does not have drivers for the Allen Bradley Control Logix PLCs.Note:

1. First, create a new OPC Client object. Choose .Object>>Create>>OPC Client

2. Choose the . The server is an (DLL), so make sure that you choose this server type. The browsing method can be either or . Make theRSLinx OPC Server In-Process Server Disabled Flatdefault access path equal to the topic name that you defined in . Click and open the Object Explorer.RSLinx OK

3. Drag and drop the onto your front panel. The dialog box should appear.OPCClient1 Insert Expression

4. Complete the expression by typing the item you are trying to read from the server, for instance, OPCClient1.O0:0. Notice that there is a dot between the tag name and the item name.

You can also type the access path by adding the ‘item name’.‘~access path’. Some servers use the access path, so you can type explicitly, if you want.

Another method is to select and type the item name in the field. Add an alias, but do not use a colon or a dot. In this case, the Object Explorer will have your aliasEdit Database Memberavailable, so you can drag that and drop it onto your control panel.

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NOTE: Lookout 3.8 users must define the access path in the description field of the database. Because RSLinx does not support browsing, you have to type the access path manually. The formatfor that is: ~~[Topic name]item. For the example above, use ~~[ML1500]O0:0. You should also change the Cache Update Rate to at least 2 ms, otherwise your CPU usage will approach 100%.

4. Connecting LabVIEW to RSLinxLabVIEW itself is not an OPC Client, but it can be used to communicate to OPC Servers through the VIs. DataSockets have an OPC layer, allowing you to read and write to an OPCDataSocketServer from LabVIEW (or LabWindows/CVI).DataSocket is a technology based on TCP/IP composed of two elements: the DataSocket API and the DataSocket server. The API provides an interface for different data types, converting thedata into a stream of bytes that can be sent across a network via TCP/IP. To learn more about DataSocket, visit National Instruments web page at www.ni.com/pdf/wp/wp1680.pdf.

The following is a brief example of how to connect to from LabVIEW using our example VI.RSLinx OPC Server

1. Launch LabVIEW and open opc.llb in the ...\National Instruments\LabVIEW 6\examples\comm folder.

2. Open NI Demo OPC Client.vi.

3. This VI can connect to any OPC Server using DataSocket connection. Next, connect it to . Set the to be , and the in the formRSLinx OPC Server Server Name RSLinx OPC Server Item Name[Access Path]Item. In this example we are trying to connect to register O0:0 using access path ML1500 defined in RSLinx, therefore the item name would be [ML1500]O0:0.

4. Click the run button when you are ready.

You should see the register data that you just connected to.

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5. Connecting the LabVIEW DSC Module to RSLinx1. Launch LabVIEW and open the Tag Configuration Editor by selecting .Tools>>Datalogging & Supervisory Contol>>Configure Tags

2. Click the icon and select . When the dialog box appears, enter the as shown.Create Tag Analog Tag Analog Tag Configuration Tag Name

3. Click the tab, choose the , ( OPC Server in this case), and click the button under .Connection Tag Access Type Server Name RSLinx Create I/O Group

4. Type in the and enter the and the , and click .Group Name Update Rate Deadband OK

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5. Click the button in the dialog box, and enter the and .Add Analog Tag Configuration Item Name Access Path

You can either create new tags by clicking the button in the window, or click to go back to the main window where you should see the items youCreate Next Tag Analog Tag Configuration OKjust created. Save the scf file.

6. Create a new VI; go to . Make sure the is also launched in order to monitor tags.Tools>>Datalogging and Supervisory Control>>Monitor Tags Tag Engine

7. Within the , you can choose the created tags under your computer name, and monitor the data obtained from the PLC. Now, you should be able to write your own LabVIEW codeTag Monitorusing the tags from you scf file.