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Is it possible to "ignore" UniStream PLC Uni-I/O hardware configuration?

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A problem which did not exist with Vision series, but exists in UniStream PLC:

- You want to test some new PLC code.

- In the field, there is USC-B5-T42 PLC installed and working.

- But you have a USC-B5-B1 to test out your code (for example).

There is no simulator in UniLogic. Only way to test your code is to load it into a real PLC.

But problem is that UniLogic doesn't allow you to download a user app if PLC model is different. For example downloading a T42 into a B1 version of PLC and vice versa. It means you basically must have each type of USC PLC on stock to verify certain application modifications, or to do it on-site. Alternatively you just forget about having onboard I/Os on the PLC, and only go with B1 variants.

A solution to this could be as easy as putting a checkbox in UniLogic settings, to report I/O mismatch as warnings, not compilation errors.

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  • MVP 2023
On 3/27/2024 at 7:35 AM, Flex727 said:

Just change the PLC model in the program temporarily to test, then change it back.

Unfortunately UniStream will stomp on your program if you try this.  If you change to a model that has a different I/O configuration then you have to delete any reference to onboard I/O points that are different.

I would make some buffer input and output bit arrays that match the size of the -T42 onboard I/O.  Then do a search and replace (Edit tab) for each real I/O point and replace it with the buffer bit.  Finally, when you want to put it back in the field add a couple of blocks to copy real inputs to your input bit array and your output bit array to the real outputs. 

For example - 

Original code:


Code for the -T42:



After deleting rung 2 I was able to change the model to a -B1.

I realize it is a bit of a pain in the butt to modify your program this way, but it will work.  You do what you can with the tools you have.


Joe T.




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Okay, thanks @Joe Tauser, that sounds like a sensible solution.

I noticed option "IO Configs" in Uni-I/O configuration, but it's sad it only refers to add-on modules, not to primary controller configuration. Would be great if it could be somehow updated to work with controller variants.


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