CraigS

1756-IF16 powerup faults

6 posts in this topic

I have two analog input cards that seem to take turns faulting on a powerup. 
The odd part is that sometimes I can power the rack down at the power supply and re-power and they come online just fine. 
it will fault 16#0204 connection error and will not re-cover from the card online without re-powering.
This is a new installation that has had this random problem. I have a 1756-L71 processor. Both cards are at their revision 1 setting. 
Disable Keying, Data connection, single-ended data-No Alarm. Float data format. I have moved the packet Interval (RPI) form 750 ms to 18 ms. Didn't seem to matter. Studio 5000 version 33

 

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I have had a similar thing happening but with 1756-IT6I2 thermocouple cards.  My system uses a 1756-L72 with v21.011 firmware.  My cards on on a remote rack with 1756-ENBTs communicating between the racks. My system has done this erratically since it was launched.  When we power down the remote system, sometimes the whole system comes up normally and other times, one or more of the IT6I2 modules will come up faulted.  We usually have to remove and reseat the individual cards.  This has happened only with the IT6I2 modules and no other analog or digital modules.  We have tried changing the rack, the ENBT and cards.  I will also mention that it is not repeatable, meaning that it is not always the same card or cards that fault.  I have multiple IT6I2 cards in the main and remote racks.  It never happens in the main rack (where the CPU is).  Sorry my response is not a solution.  I am adding my comments in case others have seen this and to see suggestions if there are any.  Good luck with your situation.

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It may not apply to you guys, but there's a tech note (access level: TechConnect) about "1756-IB16ISOE Modules Randomly get 16#0204 on Power up and Download":
https://rockwellautomation.custhelp.com/app/answers/answer_view/a_id/602867/loc/en_US#__highlight
It's not a very well-edited tech note with some run-ons and incomplete sentences, but the gist is to flash the firmware of the modules to a different version. I'd check the release notes for the different FW versions of your modules to see if this issue is mentioned and which FW version it starts with. Then choose an older version (or a newer one if it's been fixed...).

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I have duplicated this rack layout here in the factory.
I have used 1756-If16 cards that have faulted before.
With the same program installed as the other line, I can power up the rack repeatedly with no faults. 
Is there way to troubleshoot this backplane?
 

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3 hours ago, CraigS said:

...
Is there way to troubleshoot this backplane?
 

Does the duplicate system you built have the same power supply and chassis size? If so, swap them one at a time to see if the problem stays or moves. If you swap both and the problem stays, then go through your power supply and chassis grounds. And the grounding of the analog signal shields. It's not unusual for noise to cause random weirdness.

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