Mesa 7I76EU TB2 not working right (TB3 works fine) – need help diagnosing

Hi everyone,I’m very new to LinuxCNC and Mesa boards, so I might be missing something basic here, but I’ve been stuck on this for a while and could really use some guidance.I’m working with a Mesa 7I76EU and setting up stepgens in LinuxCNC. When I use TB3 (channel 4), everything works perfectly. The motor moves in both directions, the direction signal changes correctly, and I can clearly see step pulses on the oscilloscope.The issue is with TB2 (channels 0–3). No matter which channel I use, I don’t get proper behavior. At first, measuring to ground made it seem like there was no voltage at all, which confused me. Then I realized these are differential outputs and started measuring across the pairs instead.On TB2, I can see step pulses across STEP+ and STEP− (about 5V differential), so the channel is definitely active. But the DIR signal (DIR+ to DIR−) stays constant at about 5V and does not change when I reverse direction. Also, the step pulses only show up when jogging in one direction, not both.In HALShow, the stepgen for that channel looks active. Enable is true, velocity command changes sign when I jog forward and backward, and position feedback and counts are updating. So from LinuxCNC’s side, it looks like the commands are being generated correctlyWhat’s confusing me is that TB3 works perfectly under the same setup, but TB2 behaves like this. At this point I’m not sure if this is something I’m misunderstanding about configuration or differential signals, or if it could be a partial hardware issue affecting only TB2.Has anyone run into something like this before? Any suggestions on what I should check next would really help.Thanks a lot

Is it possible that you have the incorrect step mode chosen in your hal file?

(step/dir is mode 0)

Yeah i checked it in halshow under parameters
step_type is 0

The signals are differential but can be used single ended
That is DIR+ and DIR- should both change voltage when
the direction changes but one should change from 0 to 5V and the
other from 5V to 0 (relative to ground)

Measured differentially, you should always measure either
+5V or -5V across the DIR+,DIR- or STEP+,STEP- pins.

I measured again

from +5V to DIR+ = 5.13V and drops to exactly 5V when jogging in the negative direction


from +5V to DIR- is always at 0V That's for all channels on TB2 1, 2 and 3

Do you think i got a faulty board, Sorry this is getting so frustrating