Allen Bradley DH+ network with RSLogix OPC server


Thread Starter


In order to establish communication with A-B PLC 2/30 and be able to read /write data from/to this PLC using OPC server we have established a DH+ network using a 1785-KA3 Module on PLC side and a DLPCIe card on PC side. As OPC server we used RSLinx to read/write data from/to PLC. To achieve this goal we also needed to introduce a communication zone to PLC by adding some rungs (I can send snapshots of programming terminal if needed). After adding these rungs and restarting the PLC, using RSLinx on PC side, the PLC node has been successfully and automatically detected by the software (RSLinx). But the problem is that when we try browsing any data on the PLC using any OPC client (like OPC Quick Client), we are not able to see any data available about any block or bit of PLC. Does anyone have any idea about this task?

Gerald Beaudoin

First thing I would check: Does the version of RSLinx support the communication that you wish to use? The Lite version will communicate with the PLC, but may not support read/write via OPC. We had a similar kind of situation that required a "Pro" license instead of "Lite".
Hi AM,

In my opinion, there are 2 possibilities :

1. As Gerald guessed, you dont have "Gateway Licence" for your RSLinx
classic, so OPC Topic is not activated yet. Check your RSLix licence type, you can see your RSLinx type at RSLinx tiitle bar.

2. PLC-2 do not support internal tag database browsing by OPC client like newer PLC such as PLC-5 or Controllogix. Please try to add tag to be accessed manually.

Here is example using KEPware :

Hope this helps