5i25 encoder problems

Hi all

I'm building a plasmacutter and it went pretty good so far. But now I ran into a problem. I'm using a mesa 5i25 in combination with the 7i76. I'd like to connect a mesa THCAD300 to the 5i25s hardware encoder. So this would be my connections:

7i76 TB3 PIN 1 GND connected to THCAD300 GND
7i76 TB3 PIN 6 +5VP connected to THCAD300 +5V
7i76 TB3 PIN7 ENCA+ connected to THCAD300 FOUT+
7i76 TB3 PIN8 ENCA- connected to THCAD FOUT-

No plasmacutter or voltage source connected so far. And this setup causes LinuxCNC to crash.

In fact as soon as I connect cables to the TB3 PIN7 ENCA+ and TB3 PIN8 ENCA- pins, LinuxCNC crashes. Sometimes after 20 seconds. Sometimes after 2 minutes but it always crashes at some point when those two pins are connected to a cable. Even when I do not connect cables and just touch the pins with a multimeter, it can cause a crash. There is no error in LinuxCNC. The program just stops working and wont react to any input. If I do not tinker with these pins, everything runs just fine. But as soon as the 5i25s hardware encoder comes into play, its over. Strange to me is, that it is no an instant crash. It always takes some time until the programm ceases to work. If I have a look at the hm2_5i25.0.encoder.00.counter in HAL show, the value changes from -1 to 0 to 1 randomly when cables are connected. So the encoder seems to work.

So I hope it's not defective hardware. Hope you guys can help me out. I'm not sure what other information I can provide to you about the problem.

Thank you for any input.

That's a pretty weird error, if this is a RTAI based system, can you post the results of
dmesg after a failed LinuCNC run?

If this is a Preempt-RT based system, starting LinuxCNC from the command line
will print any error messages on the terminal

Thank you for the answers

I've disconnected the THCAD300 und just let the cables attached to the ENCA+ and ENCA- pins of the 7i76. Following the link below you can see two videos, one of the running state which was stable for a few minutes and one of the failure state. The failure occured apparently random while not interacting witch the machine. In this state, LinuxCNC wont react to any control commands. It's possible to open HAL show and so on, but the rest of the buttons like E-Stop won't work anymore. As soon as I click on a button at this point, the message USRMOT: ERROR: command timeout starts to appear on the terminal. When I use LinuxCNC without cables attached to ENCA+ and ENCA-, the machine runs stable.

imgur.com/a/ELD6Lu4

Greetings
Sandro

Can you comment out:

net plasmac:arc-voltage-in hm2_5i25.0.encoder.00.velocity => plasmac.arc-voltage-in

And try again, to see if this is a low level problem or something higher up

Thanks for the additional inputs

Can you comment out:

net plasmac:arc-voltage-in hm2_5i25.0.encoder.00.velocity => plasmac.arc-voltage-in

And try again, to see if this is a low level problem or something higher up

I did that, but unfortunately with no luck. The bahaviour is still the same. Even if I run the base machine configuration without any plasmaC related components, the problem remains.

Is the cable to the THCAD shielded ?

The cable has a shield but which was not connected to the ground. Which I did now But it did not help.

What I also tried: I changed the number of encoders from 1 to 2 in the .hal-file and checked with ENCB+ and ENCB-. No luck there either. So to summarize, only if I attach nothing to those encoder pins 7,8,10,11 of the MESA 7i76 TB3 and don't dare to touch them even with a multimeter, only then the machine runs stable so far.

Hmm sounds like a hardware issue of some kind, maybe 5I25 maybe PC
Can you try another slot in the PC or another PC?

Okay I will try another PCIe slot. Maybe I can also set upt another computer.