Smart serial card remote error = (27) Over Current

We're running a 7i76e and a 7i85s daughter board to control 8 stepper axes and 10 digital outputs.

We've started to notice an odd failure that happens occasionally. Some of the digital outputs just stop working, but not all of them.

All of the digital outputs are going through relays, to protect the Mesa cards. The particular relays are these ones www.mcmaster.com/8262t11 . They have a 12mA control current, which seems completely within the capabilities of the Mesa cards. (See page 24 of www.mesanet.com/pdf/parallel/7i76eman.pdf)

We noticed this error when we added the 7i85s to the mix. (Before we had some of the motors being controlled by arduinos while we were waiting on a replacement 7i85s.)

Any things we should look at to try and figure this out?

Thanks.

The errors on screen are:

hm2/hm2_7i76e.0: Smart serial card hm2/hm2_7i76e,0.7i76.0.0 remote error = (27) Over Current

hm2/hm2_7i76e,0: Smart serial card hm2/hm2_7i76e.0.7i76.0.0 remote error = (8) Remote fault

I dont think I have seen this without an actual external fault,
so I would see if you get this error with nothing connected to the outputs

If you get this error with no loads then it indicates a 7I76E fault
a 7I85S should have no effect on this error.

When a overcurrent event is detected on an output chip, that particular
chip is disabled (so 8 will be disabled at once)

Hi.
I have had the same problem on a 7i77 and 7i71. At first I thought it was due to faulty flyback diodes on the relays but it happened again after replacing them. I then installed a switch mode PSU for the 24v supply to the Mesa cards instead of the old transformer-rectifier ps that was in the machine.

After this one or two pins failed again but it seems to have stopped now. The machine is also at a different location now and it has not happened again.

The pins that failed as stays "on" even if lcnc is closed and pc switched off. The damage is permanent and does not reset on power-cycle.

Also, the pins that failed are individual pins, not all the pins on that header. For example 02 fails, but 00 01 03 04 etc would still be operational.

Not sure why it stopped, could it have something to do with a ground/earth connection?

Henk

I'm trying to understand this... What would those external faults look like? A short? Something else?

Could it be caused by a voltage dip from the power supply?

So I notice no change in the 8 stepper motors being driven. However, we do notice that some, but not all of the digital outputs stop working sometimes after an error occurs. A linuxcnc restart will fix the problem.

Is there are place I can read some more on these errors so I can try and debug them?

If you had failures in both a 7I77 and 7I71 it does suggest a power issue of some kind
One thing to avoid is hot- plugging or switching the field power to the 7IXX board
This will cause voltage transients that can damage the output chips

They could be caused by an external short or by a bad/failing output chip that has been damaged somehow

That's why I suggested disconnecting the output connectors(to see if its an internal 7I76E issue or an external issue like an intermittent short)

So to report back... I'm having trouble duplicating any errors. It seems things only fail when the operators are using it. I was looking over the wires again, and I did find a loose wire going to one of the relays. Perhaps this loose wire caused some intermittent problems, but it doesn't explain everything...

We're going to do some better logging so we can try to figure this out as future problems creep up.

I've been doing a bunch of testing and the errors have been much less. However I did witness a remote error = (26) Over Temperature error. I'm going to add some forced ventilation and try and solve that problem.

I added a couple of fans to the cabinet. One generally exhausting the warm air, and another muffin fan pointed right at the 7i76e. We didn't see any errors after a full weekend or the robot bar pouring drinks, so I'm hopeful that we've found the solution.