omron sysmac c20

Hi to you all, hope someone can help.
I have just purchased a slab making plant which uses the c20 to control certain actions, my problem is when i power up i get a warning light on the control box door saying that the emergency stop button has been pressed. How can i reset it

If you have a display panel, some displays retain the history of the last few faults on the screen. With just a warning light burning, check these items.You may in fact have a locking type Emergency Stop Push Button still pushed in, try pulling them (if more than one) out. There may also be a safety stop on a guard that has been pushed or pulled or removed, look for that. If that doesn't fix it you will need to check each Emergency stop button for proper functioning. Most use Normally Closed contacts so you should check to see if continuity is maintained with all the contacts on all the stop buttons.

Is there a connection in the panel for an external emergency stop button? If so it would normally be a normally closed contact type. Either install an external e/stop with N/C contact or bridge the terminals together where the remote e/stop would normally connect. I have seen that one catch many a sparky out.

I would say its not on the plc, an E-Stop circuit should be hard wired only (unless its a safety PLC). Was the machine supplied with drawings? Have you any E-Stop relays in the panel? Stupid question maybe, but is there a reset button on the main panel.

The Emergency Stop function is not an internal part of the Omron Sysmac C20 PLC, nor is it normally an internal part of any PLC. The PLC program probably does monitor the Emergency Stop switch and display the light.

To reset the switch you first need to make sure it exists. It could very well have been disconnected and removed in order to move the slab maker. If you do find an Emergency Stop switch, then check the wiring connections. You could have a loose wire, since the Emergency Stop function is usually a closed switch. A loose or disconnected ES wire will show up electrically on the PLC the same as "Emergency Stop Switch Pressed".

Otherwise, to reset most Emergency Stop switches, pull out the knob, or pull out while turning the knob.

Many thanks to you all for your suggestions and advice, I will investigate all possibilites asap and let you know the outcome.
Fingers crossed
Kind Regards Baldeagle2

Hi to all you kind people who gave your advice on my problem. I am pleased to say that after checking all the emergency stop buttons and the wiring to them, I found that one of them was open circuit, hence the warning light,So many thanks to you all.
Regards
Baldeagle2

Great, glad to hear you sorted the problem