Adding a I/O module issue

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      I have a SLC 5/05 processor. It has been in service for years. I added a 1746-!B16 to it. I configured the additional card and everything looks good and back in run mode. No errors. I realized that the 1746-NI8 Analog card has no values in program. I tested the inputs and everything is good feeding the module. I remove my new module back to original and everything is good. I then add the card to a different slot. Same problem. I even tried adding a different card and had the same problem. I never seen this before. When I add the new card, I have no additional logic using it either. Has anyone seen this problem?

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        Go online and save your program (in the format that you want to have with the new module configured).  After saving program, you might try to initialize the processor by pulling the battery and shutting off the power to the processor.   Replace battery and power chassis back up (the processor should be initialized with no program now).  Now download your saved program.  I have had some strange things happen where I have had to pull the battery and perform a fresh download to an initialized processor to fix some unexplainable issues.


          Hi there and welcome to the forums. The problem could be stemming from the fact that while the NI8 module only takes up one physical slot it takes up multiple logical ones. Each channel will take up one word or 16 bits of memory. Since there are 8 channels that’s basically an entire logical rack (8 words) for just that module. Unlike standard discrete IO modules that take up only one physical slot/one logical word.

          Depending where you’re placing the new IB16 and how you’re mapping it, it could be overlapping the logical slots of your NI8 which is why you’re seeing zeroes. Something to look into.

            Karma: 172
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            Its an analog card – the configuration is probably store din the analog card and not in your code – the settings and adjustments .
            You said ” I realized that the 1746-NI8 Analog card has no values in program.”  you say it was working fine and had values before you started with the new card or after the new card  or at both times.
            You did not mention if you moved the analog card or not. Remember that card is configured differently  than how it would be on a SLC or Control Logix .. it might be in the analog card configuration – so you might want to check that first – is the analog card on the end of the line or somewhere else ?
            Also the power on the bus – power supply under rated ??

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              I think Fred and Ken both have probable fixes. I’ve had the same issue once and it was because of like Fred said it was take up 2 slots virtually but the software didn’t make that clear and it accepted my wrong configurations. And I’ve had similar issues on other platforms and it  was because the power supply was going bad one time and it was under rated the other time.

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