Anyone familiar with Mitsubishi FX PLC

Have you switched the PLC "off" then plugged in the programmer?

On some of the MELSEC FX PLC's, there's a screw terminal named 'RUN' to which there is probably connected 24VDC. Disconnect this cable and connect it to 'STOP' terminal instead. Hope this helps!

Yes, I tried that, and every combination of power/connection/switching I could think of.

I already looked, there's no wire(s) to the "RUN" terminal at all, but thanks for the suggestion. It does seem odd that the "RUN" connection isn't needed to keep the unit running, but I was very careful in verifying there was no wires there and that I was looking at the correct terminal.

In thinking back last night I recalled that we used to put a EEPROM cassette in some of the PLC's, and they had a "Write-Protect" DIP switch on them. I'm going to the site today to see if this one has an EEPROM and if so whether switching off the protect switch allows the unit to stop.

Take a look at the status/ control bits. Manuals are available from the Mitsubishi web site (sometimes funky to find).

On FX1N, FX2N and FX2NC PLCs you can set the M8037 bit to force a remote stop.

Norman

If you can find out *exactly* which FX PLC you have that will help quite a bit.

Are you sure you you have an original FX?? There was a huge range, starting with the FX series, through the FX0, to the things they have now. The FX needs the run input - the FX0 doesn't..

The EEPROM write protect won't help. If you have an FX, you should be able to stop it by holding the [WR] key down on the programmer whilst powering up the PLC.

HTH, Cameron:-)

Take a look in the manual for the specific FX CPU that you have, here's a list of most manuals:

what model FX?

I found out how to do it. You hold down the "W/R" button while powering up. It works, but oddly enough, I don't remember having to do that originally. The elevator is back in working order now, the new VVVF drive is happily running the motor to transport people up and down.

Not sure, but I know there was no RUN signal needed.

Heh, where were you when I was frantically pushing every damn button on the hand-held trying to stop the thing? You're quite right, though, that does stop program execution and that's exactly what I did to edit the rungs.

Don't know, but I *had* the big manual for the PLC and it didn't help. What I needed was the book for the FX 10P-E hand-held programmer.

I may just have a copy of that at work, I'll take a look today.

sQuick..

Not necessary, thanks, the problem is solved. I'm almost glad this situation arose, I was unaware of this group and find much of it fascinating reading. I wish I'd had access to it back in the early eighties when I was first struggling with PLC application to elevator controls but I see it wasn't newgrouped until '92.