We've recently come into a weird issue.
We have a PLC communicates via devicenet to this I/O module:
http://www.turck-usa.com/illustrations/F0175%20(sheet_1).pdf
It fires 4 different outputs which are signal wires to 2 separate reamers. 2 for "ream cycle start" and 2 for "spray anti-spatter".
The power for these outputs comes in via Aux power from a 24v supply inside the Fanuc robot cabinet for Robot 1. This also gives power to the reamer itself.
There are 4 total welding robots inside this cell.
Robots fire DOUT 30, which goes to PLC and from PLC it sets the bit for that module to fire the reamer.
These robots were just installed, they use to be old panasonic robots, and now they put in new fanucs. This problem did not occur before the new robots were put in.
Problem: When Robot 1 strikes an arc, the reamers will start cycling and spray their anti-spatter until Robot 1 finishes it's weld. It will do this for every single weld on Robot 1.
Troubleshooting so far:
1. I watched PLC, DOUT 30 never came on from robot, and PLC never told reamers to fire.
2. When welding manually with the teach pendant in hand and inside the cell, it does not fire the reamers, even though the reamers still have power. I can turn on DOUT 30 and reamers go just fine.
3. There is 5 volts between the cabinet (ground) and negative side of 24v power wire.
4. Measuring the ohms between an output pin, and 24v wire will cause the output to fire. It does not do this on any other identical cell.
5. There is a Pheonix Contactor safety relay right beside the 24v supply in top of fanuc cabinet, they are using the ground wire as the return side of coil (I believe? It's going to pin A22, and removing it causes contactor to drop out).
Honestly I have no idea what is causing the issue, we have tried pretty much everything. When I go back into work, I'm going to try putting a pull-down resistor on each output.