New cell from an integrator, commissioned last month. Conveyor inside a fenced cage, one guard door with a 440K tongue switch, safety on a Compact GuardLogix 5069-L306ERS2.
Open the door, conveyor stops, fine. Close the door and the conveyor starts running again on its own, no reset press, nothing. Our safety guy watched it happen and went pale. If you're inside the cage and someone shuts the door behind you, it runs.
I checked the door switch, actuator, tongue and mounting, all tight and clean, and it makes and breaks like it should. Production's suggestion is a horn that sounds before it restarts.
Our laptop guy is off this week, but I can get online with the spare if somebody tells me what to look at. Pretty sure it's not the switch, any pointers?
Program, not the switch. Safety routine, find the DCS instruction for that door. It has a Restart Type parameter, Automatic or Manual. Which is it? And is there a reset button on that cell anywhere, and what is it wired to?
Got online with the spare on the 5069-L306. DCS for the door says Restart Type: Automatic. There's a blue reset button on the panel outside the cage but from what I can see it only goes into the E-stop DCS, not the door one.
Then it's doing what it was told. Automatic restart means the function re-enables the moment the door closes, no human in the loop. Fine for a hatch nobody can climb through. Not for a cage a person can stand inside with the door shut behind them.
You need a monitored manual reset: door closes, nothing runs, somebody outside the cage who can see the whole zone presses reset, then it runs. Restart Type goes to Manual on that DCS and the blue button gets wired to its reset input too. The horn does nothing about the person in the cage.
That's a safety task edit, so it's the integrator's job with your safety guy, then re-test and a new signature. There's a writeup on the interlock side here: https://plctr.com/implementing-plc-safety-interlock-systems-in-industrial-environments/
And one detail so nobody thinks the button is broken afterwards: the reset on those instructions acts when the button is released, not when it's pressed, if I remember right. Standard wants it that way. Safety task opened up for editing, tested, new signature, written down. Not the spare laptop on a Friday.
Integrator on the phone. Says Automatic was "what the customer asked for", which nobody here remembers asking for. He's coming Thursday. Cage is locked out until then, tag on the door.
Good. And the reset button goes where you can see the whole cage.
Integrator came out to the 5069-L306 cell. Restart Type on the door DCS set to Manual, blue button wired to its reset, button already outside the cage with a view of the whole thing. Safety task re-tested with our safety guy, new signature in the file. Close the door now, nothing moves until the button, and the button works on letting go like dave said, took me three tries to notice.
It has been on automatic restart since the day it was commissioned, which is why shutting the door started the belt.
Nobody here knows who asked for Automatic, and the integrator's checklist has it ticked. Thanks ronh55 and rsdave.
Marking solved.
plctr.com team