View Full Version : Missing Comm Return?
01-14-2009, 09:41 PM
About 70% of the time I get a "Missing Comm Return" error when I use the key pad function to move the car around. It always happens at the end of a move, everything freezes up, I get that error, and then I have to restart up everything. I canít figure out what it is, I donít any other problems with it other than that. Any ideas?
Thanks in advance.
01-14-2009, 10:29 PM
try rebooting the software. Do a speed test to make sure you have a good connection. Open your control box up, and make sure all the green lights are on when you are moving the gantry around. For some reason one of my stepper motor connections on my motherboard has always been a little touchy, and I think that has happened before.
01-15-2009, 10:48 PM
Matthew, I was just wondering whether the suggestions Justin posted cured your problem. I have a PRT w/4G board and having identical problem occasionally with the arrow keys. Error occurs even though the spindle and dust collector aren't even running.
01-15-2009, 10:56 PM
Does your bot have adequate grounding?
01-16-2009, 05:04 AM
I havenít checked out Justinís fix yet, I was going to investigate tomorrow.
Jack - It is grounded, but not above and beyond by any means. I donít run a dusk collector on it so I didnít think I needed additional grounding.
02-20-2010, 06:34 PM
Matthew, Did you ever find a fix for this? I'm struggling with a new install and have the same problem when I run a file (plenum cut file). I've done the comm test and get around 70.4%. I've tried it with and without the dust collector running. I've checked the connections in the control box and I've rerouted the cabling. I've tried 3 different PCs and have downloaded the latest control software. I have NOT done any special grounding other than suggested in the install manual. What I think I'm seeing and haven't confirmed is that my problem may be thermal related. When I first start in the morning I seem to be able to 'run' longer before the "Missing Comm Return" appears. Later in the day I can 'run' for sometimes only a few inches before the error. Anyhow, my level of frustration has just about peaked! Does anyone have ANY suggestions for when I try again tomorrow?
One word "grounding". Make sure all your grounds are good and TIGHT and there is no corrosion anywhere. Especially make sure your computer is grounded to the controller box.
02-21-2010, 06:26 PM
I will ground and re-ground as suggested (x100)
signed, Bart Simpson
I ran a 12ga solid copper wire from the chassis of my dust collector (Delta) to the far side "X"rail, then to the near side "X" rail and to the ground buss in the control box. Problem solved!!!!
06-28-2011, 07:50 PM
We have been having lots of trouble with the bot lately with it "freezing" or locking up or jumping steps and ruining parts usually giving us a "missing com return" and requiring a full restart and we have not only been unable to repeat the problem consistently but also unable to find a solution until now we hope.
We have tried grounding to the max. Used different computers (no change) and switched our power source. Nothing worked. I have not been using the machine full time but today I think we found the problem.
We could run files in the air just fine with the router off but as soon as the router motor was turned on the system started acting weird and would either just freeze or give a missing com return. As I said though, this was not consistent and didn't happen every time. Our problem accounts for this.
We have been lackadaisically resting the Z-plate on top of the carriage when not in use but today we tried keeping it and the clip isolated from everything and PRESTO no problem. No glitching, no freezing, no missing com return. We now have the z-plate held with a rubber tip spring clamp bolted to the carridge and isolated from the carridge. Chattering Z-plate was causing spurious transmissions AND as a test, we could cause the machine to glitch by tapping the Z-plate to the carriage while it was running.
It took us a long time to solve this one so if anyone else is having missing com return issues. Check your Z-plates and make sure they are not chattering away out of place on top of your carriage.
06-29-2011, 09:46 AM
I have the buddy, which does not require additional grounding but occasionally i have the same problem. i will pay attention to my z zero plate.
06-29-2011, 10:55 AM
Something that I did not know about the Zero Plate, that it has current 5 point something Volts DC and if it is grounded it could create all types of problems.
I should have said while running a file
06-29-2011, 12:29 PM
Instead of the supplied holder or a clip, etc. I've been using some adhesive backed flexible magnet on the underside of the zero plate and just stick it to the side of the gantry face.
Been that way for 10+ years with no problem. Just mic the plate with magnet applied and enter that into the "my_variables" file.
06-29-2011, 03:37 PM
I store my Z zero plate with the grounding clip attached. Then it doesn't matter where it ends up.
06-29-2011, 07:01 PM
I screwed a piece of aluminum angle onto the top of the z axis plate in the back and screwed a board to that that sticks out far enough to attach the vacuum blast gate to and has the zero plate mount between the blast gate and the z axis plate. The zero plate is completely isolated by the plywood. All com loss problems stopped as soon as I did this.
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