Description
Some or all items in the OPC Client are disabled upon startup when using OPC Client to communicate to a ControLogix PLC. OPC Client will not automatically enable items upon startup of RSLinx even though the Auto Start, Auto Enable, and Enable Children option are selected. When using the Server Diagnostics window to troubleshoot issues, you see errors similar to the following: "Unable to add item ItemName to group GroupName, Invalid ItemID", where ItemName is a valid item configured in the OPC Client, and GroupName is a valid group name configured in the OPC Client. This error indicates that the client is unable to resolve string syntax to RSLinx OPC server.
Resolution
Ensure the correct syntax is used in the OPC clients. The Item ID field should only consist of the RSLinx Topic Name in square brackets (i.e., [RSLinxTopicName]), and immediately following is the file number, a colon and then the register (e.g., N7:110). The Access Path field should consist only of "No Access Path" as RSLinx does not use this information.
Examples
Access Path Field: No Access Path
Item ID: [RSLinxTopicName]:N110
and
Access Path Field: No Access Path
Item ID: [RSLinxTopicName]:B14:0
NOTE: You can use RSLinx test client located in the RSLinx program group to communicate to the same item when troublehooting problems. If communication is good, make note of the syntax for the item in test client and compare it to the Item ID in the OPC client to ensure they are consistent.
See Also
