1747SN and BTR/BTW to 1794-IE8

I am having trouble with an existing SLC5/05. It was working fine but after power cycle, we lost data to all but 1 1794-IE8 module. I looked at the program and there's a BTR instruction for each IE8 that is has rung condition true but the EN DN and ER on the right side of the BTR instruction is not on. There is no BTW instruction. We've swap modules with no luck. Any idea?
Thanks,
John

I know when using 1794-IE8 with a PLC5, you need a BTW to configure the card on 1st scan, so when you power up with a new card, it gets configured automatically. It's probably the same with a SLC. Get a manual for the 1794-IE8, and the 1794-ASB from ab.com and check this out. The BTW probably needs to happen to set up the voltage/current selection for each input channel.
Also, make sure your 1794-ASB isn't faulted. Most of the time it should be configured to allow the processor to restart it after a fault. BE SURE YOU'RE LOOKING AT THE CORRECT MANUAL FOR YOUR SERIES/FIRMWARE ASB. A/B has changed some of the functions of the dipswitches at least twice over the years.
Hope this helps, Paul C.

there's a BTR instruction for each IE8 that is has rung condition true but the EN DN and ER on the right side of the BTR instruction is not on.

Click to expand...

this sounds like the processor might not be scanning your rung ... hard to imagine why it would have worked before a power cycle but not afterward ... but it's easy to check ... if you're not sure how, just copy the rung into the very top of Ladder File #2 ... this one is always scanned on an SLC system ...

if all else fails, think about posting your .RSS file ... maybe we can help you spot something ...

Sounds like the IE8 is not configured

I Think the IE8 series B needs a configuration block written to it in order to work See Pic

If you can find no BTW instruction then do a search for the corresponding #M file as it may have been programmed in ladder rather than using the BTW instruction

This is an example of an slc BTR & BTW using the IE8

Its an Example from Rockwell