Using symbol instance addressing doesn't work with Micrologix 1769-L32E

[JustAnotherBitBanger]

Using Rslogix 5000 Data Access manual as a reference

I keep getting 'Service Not Supported' response when using symbol instance addressing to read a tag (Instance ID). Symbolic addressing works fine (Tag Name).

This is for a compactlogix 1769-l32e

Any idea why that would be?

 

[Ken Roach]

Welcome to the PLCTalk forum community !

What firmware are you running on the 1769-L32E ? Those are a second-generation CompactLogix and support up to v20.x firmware.

I found a note in the Knowledgebase (QA27891) that support for symbol instance addressing using function 0x4C started in v21 firmware. I found a mention of that also on page 16 of the Logix 5000 Data Acess Programming Manual 1756-PM020 that you're using.

If your software system needs to support older Logix 5000 family controllers, you'll have to use ordinary tag names or check for the version before using symbol instance IDs.

 

[JustAnotherBitBanger]

Thanks. I missed that.