Q64DAN no value

[Carples 0]

I have a Q64DAN module. It has work fine for 12 months but recently it started to play up. when I push a value into the auto refresh register the register stays at 0 on 2 channels. The third channel is working OK I got the 2 troublesome channels working the other day but they stopped again. What could cause this probelm

[Crossbow 297]

Are the output bits to enable those channels turned on? The analog card occupies 16 bits, check the allocation of the Y addresses for the analog module and ensure that the proper Y bits are on.

[Carples 0]

Hello Crossbow yes the enable bits for the first 3 channels are all driven by sm400 on the same rung of ladder. Y40,41 and 42 I believe. They were working before, with no changes to the code that controlls them channel 3 is working. I had an error light on the module the other day, so I reset the PLC to clear it and it is still of but not working. could a out of range value cause it I have a compare statement in the code to limit value to 0 > value < 4090 which I understood to be the value limits as mentioned above the system was working before.

[RTRBURN 0]

Have you tried puting that input on another channel? Or swapping out with another Q64DAN card if you have a spare or can borrow out of another machine to confirm working card or possible bus issue on backplane board. I had a channel just go bad one day on a Q64DA. We got an error, reset plc, error went away but channel never got any response, changed load cells, still no response. We had a spare channel on the card and originial load cell worked. Swapped out card with new card and all channels worked. Had same problems with a QD75P1 positioning module a few weeks ago. The CPU was not seeing any input from the card.

[Carples 0]

I found the problem on this one. Had nothing to do with value, flag was not being triggered due to change of equipment. But when monitoring this PLC I find many registers do not display actual value. So my Analogue register showed as 0 but the actual module when monitored using Intelegent function untility there was a value. Lead me up the garden path.