PCM

[rjmah]

I'm wondering if any others are having trouble with the PCM (Pneumatic Control Module). Ours completely failed during practice day. I checked fuses and re-did the CAN network wires. Finally got a spare from spare parts and it worked. I'm just wondering if maybe the module is not as resistant to shorting out or grounding out (wiring may have touched our arm) as it could be.

[tStano]

Ours also inexplicably failed. I have no idea why, but it just stopped working, after a long time of not using it(waiting for Bimba), but having it wired to our electrical board. We have yet to take it apart and see what happened.

We luckily had time to order a new one, but it seems to me much less robust than the relay card for the cRio.

[PAR_WIG1350]

Originally Posted by rjmah

I'm wondering if any others are having trouble with the PCM (Pneumatic Control Module). Ours completely failed during practice day. I checked fuses and re-did the CAN network wires. Finally got a spare from spare parts and it worked. I'm just wondering if maybe the module is not as resistant to shorting out or grounding out (wiring may have touched our arm) as it could be.

If you suspect an intermittent short, you should definitely make fixing that a priority.

[s_forbes]

Some issues with the PCM came up over the weekend while testing on our practice robot. We were reading solenoid faults when operating a lot of mechanisms at once in quick succession, giving the flashing red signal on the status light and solenoids that no longer respond. The manual lists that combined current for all channels should not be more than 500mA, and we were running several 5 watt (12v) solenoids from previous years.

We spent some time selecting the right default position for our single action solenoids (swapping hoses and values in code) to limit how many are being fired at once. Also adjusted the double action solenoids to activate with a pulse rather than a continuous hold, which is how they were initially set up in code. This seemed to make our issues go away. Really we should be using some lower power solenoids and not so many single action solenoids for our pneumatics.

Check out the manual at Vexpro here: http://content.vexrobotics.com/vexpr...e-20150219.pdf Very handy for troubleshooting.

[Al Skierkiewicz]

When you report a failure of the PCM here, can you add a little detail? What compressor type and how big a pneumatic system you have. (tanks and actuators please)

[rjmah]

Originally Posted by Al Skierkiewicz

When you report a failure of the PCM here, can you add a little detail? What compressor type and how big a pneumatic system you have. (tanks and actuators please)

Pretty sure it was this year's compressor, two of the old small capacity aluminum reservoirs and a single solenoid and a 10 inch stroke cylinder. Now that you mention multiple solenoids, team 2013 seemed to have problems with their PCM too and they had 3 double acting solenoids.

Yes the frame shorting was addressed.

[maths222]

Those of you having problems: If you haven't yet, email CTRE at support@crosstheroadelectronics.com with as much detail as you can provide. They can probaby either help or will be interested in understanding how it failed so that they can improve the design.

[The Lucas]

On Team 365, we have a PCM that was dead on arrival (DOA). Team 4342 was generous enough to loan us their PCM while 365 goes through the RMA process.

Skipping to the cause of the failure, there is a solder joint fracture on one of the surface mount chips. This failure is unlikely to happen to any team with a currently working PCM (ours was DOA) so I will just briefly describe some of the symptoms:
First, this was a failure on the solenoid channels, compressor circuit worked fine.
Solenoids never switched on any of the channels. Webdash recorded a solenoid voltage of 3V, voltmeter could never pickup any voltage from the channels.
Initially, the channel LEDs would sometimes flash on momentarily (before a fault was indicated) and displayed some weird behavior (glowing faintly while off). Later in testing they were always off (I suspect the vibrations of the compressor made the solder joint connection go from intermittent fully off).
Frequent Solenoid Fuse faults reported on the webdash (both sticky and now). Status light was usually blinking red once. Faults were so persistent, they were difficult to clear (got some ironic Self Test messages indicating Faults with a message at the end that says "all faults cleared"). Occasionally, I could get the faults cleared and status lights normal. Once I turned on a channel (with nothing connected) the fault would return.