I want to use the OPC tag of a photo eye which is located in a Remote I/O. The problem is I am not able to see the tag in tag browser-> browse device. What might be the reason for this and how to solve it.
What controller are you using? What firmware is on the controller? What driver are you using?
If it is an AB CLX, are the tags set to External Access Read/Write or Read Only?
You really should be mapping physical IO in your PLC to controller scoped tags, and then creating ignition tags that point to those. Even without Ignition involved, you should do that as PLC coding best practice.