7i76 SSerial stopped working

Hello, all!

Earlier this year, I did a CNC conversion using the Mesa 6i25 + 7i76. Has been working great for a few months now, with no controls-related issues. A single 7i76 is connected to the 6i25 via about ~20ft of cable using the DB-25 port on the back of the card. Typically I leave the control cabinet and PC powered on (but the E-stop circuit open, which leaves all of the drives, etc. powered off).

Today I went down to use the machine and noticed a bunch of I/O and serial-related errors in the UI (I don't have the exact errors, and I didn't see where LinuxCNC logged to disk anywhere). I attempted to power cycle the machine and control cabinet, but upon doing so, I got the error:

./pencham.hal:28: Pin 'hm2_5i25.0.7i76.0.0.output-00' does not exist

Upon further investigation, it seems like the 6i25 is not detecting the 7i76 via SSerial. Field Power (24VDC) is applied, and the board is receiving 5V from the 6i25 card. I measured both power rails at the board, the 24V line was OK, the 5V from the FPGA card was about ~4.4V. I tried switching the 7i76 to use external 5V power (changing jumpers on both boards), but to no avail. It's switched back to using 6i25-supplied 5V power now. In both instances, both LEDs on the 7i76 are lit.

I buzzed out my DB-25 cables and all lines seemed OK. I did try a different (shorter) cable, but this did not seem to help. As part of this process, I also re-seated the 6i25 card in its PCI-e slot.

If I comment out all 7i76-derived I/O from my HAL file, I can get the card to generate pulses for my servos (although weirdly, the direction was the same in both positive and negative, but this may be unrelated due to my quick HAL edits).

I have attached a file with some log output showing the pin map and mesaflash outputs. The 'configuration name' is "HOSTMOT2" (I assume this is the bitfile for the FPGA?).

Any ideas? Thanks!

If the motion directions changed and you only commented out lines with "7i76"
in the hal file, that suggests hardware trouble in the 7I76 or 6I25. I would request a
RMA from MESA and send the card pair back for evaluation/repair/replacement

Thanks PCW. I figured that might be the case I'll hit them up.