Hi all,
Accumulation conveyor, PowerFlex 525 on EtherNet/IP from a 1769 L30ER. Safety relay drops the drive's STO on e-stop. Four conveyors on the cell, all wired the same as far as I can see.
After an e-stop and a safety reset this one comes up Ready and just sits there. The PLC has the run bit true the whole time, I can watch it in the tag, and the conveyor won't move until somebody toggles the run off and on from the HMI. The other three restart on their own.
I checked the parameters against a good one in CCW, side by side, and nothing jumped out, then somebody said try the firmware, so I flashed it up to the same rev as the other three and it made no difference. Is there something in the 525 that wants to see the run bit go false after an STO before it'll take it again?
Does that drive fault F059 when the e-stop hits, or just drop to Ready? And on the three that work, what's the run bit doing in the PLC during the e-stop, does it drop or stay true?
F059 on the e-stop, reset clears it. Looked at the logic on the three good ones, their run bit is ANDed with the safety OK bit so it drops on the e-stop. This one's run bit is a latch from the HMI and nothing else. Different programmer, different year I think.
There's your difference. After a fault or a safety open the 525 wants a stop and then a fresh start edge. A run bit that has been true the whole time isn't a new start, so the drive sits in Ready waiting for one. The three good conveyors drop the run on the safety event without anyone meaning them to, because of the AND.
Fix: AND this one's run with safety OK as well. The safety event drops the command, the reset gives the drive a rising edge. Exact behaviour depends on the start source and the start at power up setting, so don't count on the drive tolerating a held run.
The run and stop handling for conveyors is written up in this one: https://plctr.com/utilizing-plc-in-material-handling-and-conveyor-systems/
Added the AND. E-stop, reset, conveyor restarts on its own. Second shift ran it through a dozen e-stops, fine every time.
The run bit that never dropped was the whole thing, F059 clears and the drive is still waiting for a start edge that already happened. ANDing it with safety OK like the other three gives it one.
The firmware flash, not sure that did anything at all, it was one rev behind. Thanks priya87, vinnie86.