Recent CLX upgrade but never changed the message type

We have just recently had an "outside" organisation upgrade our AB SLC PLC with a Controllogix. In doing so they have changed all of the messages that were on a different contrologix PLC that used to talk to it over DH+ to "PLC5 Typed Read" and left the original B10:0 style addressing for the table it is reading even though it is now B10[0].

The issue is it seems to be working but we are also getting issues. Not sure if they are related to this or not?

Thanks

evilthorne said:

We have just recently had an "outside" organisation upgrade our AB SLC PLC with a Controllogix. In doing so they have changed all of the messages that were on a different contrologix PLC that used to talk to it over DH+ to "PLC5 Typed Read" and left the original B10:0 style addressing for the table it is reading even though it is now B10[0].

The issue is it seems to be working but we are also getting issues. Not sure if they are related to this or not?

Thanks

Click to expand...

It used to be DH+; how are they talking now? What issues are you having?

Can you check if they set up SLC mapping for eg B10[0] to B10? That's normally set up for communication with legacy devices that only know how to deal with SLC addressing and would explain why it is working with the message setup shown.

If so you should be able to change it to a CIP Data Table Read and just point it at the tag directly to eliminate that as a possible cause of your issues.

Someone may know more than I do, but I would think this would need to be changed to CIP Data Table Read. I see on the bottom that the path is through a card called "RIO_Comms_Card", is this supposed to be a Remote I/O application? A picture of the configuration screen might also be helpful, but again I would think that the message type would need to be CIP for two ControlLogix processors.

whoops it is still DH+

The B10 is an array of 6 INT and the Alarm_msg is an array of 6 DINT as well.

evilthorne said:

whoops it is still DH+

The B10 is an array of 6 INT and the Alarm_msg is an array of 6 DINT as well.

Click to expand...

Pretty sure even if it's still DH+, it should still be CIP Data Table Read. Is the configuration set up correctly, i.e. with the correct node number for the PLC being read, and going out of the correct channel on the DHRIO card (A or B)?

EDIT: What kind of issues are occurring? Is it complete loss of comms, some data not coming through on some messages, different data than what's expected or what should be coming through?

Yes that is all correct, and no errors on the actual message as far as I can see it is working, This basically moves data for faults so we can have and HMI in another location to monitor this area, The issue is we are getting some different faults between the two.

Is there any consistency to the differences in faults? E.g. one specific fault is always seen as a the same (incorrect) fault on the other? The fact that you have INT on one side but DINT on the other might be an issue.

As mentioned I suspect they've set up SLC mapping which allows the message instruction to function with a PLC5 Typed Read. That feels like a kluge workaround for something; for communicating between Logix processors the standard is to use CIP reads/writes

I recommend transferring the relevant portion of the B10 array to a DINT array and then changing the message setup to a CIP Data Table Read pointed at that.

plvlce said:

As mentioned I suspect they've set up SLC mapping which allows the message instruction to function with a PLC5 Typed Read. That feels like a kluge workaround for something; for communicating between Logix processors the standard is to use CIP reads/writes

I recommend transferring the relevant portion of the B10 array to a DINT array and then changing the message setup to a CIP Data Table Read pointed at that.

Click to expand...

I was wondering about this, but I've personally never done the PLC5/SLC mapping in a ControlLogix, so I didn't want to comment on that.

Not an unusual choice. Straight conversions would be lowest risk, and that means the new Logix would have to emulate the older message behavior. (Which it can.)


What kinds of issues?

Okay so a little bit of an update on this. For whatever reason they said they could not get the CIP working properly so they decided to use the PLC5 type read. Turns out that it was messing them up and moving the bits at the word level rather than the bit level. so int[1] was moved to dint[1] rather than the 17th bit of DINT[0] Hopefully that explains it well enough. Still not right though and we may have to come back and look at it later when we are not running. Thanks for the help again.