larry818 Posted May 2, 2015 Report Posted May 2, 2015 Hi, I have two FX3G plcs that died in the same panel. One lasted about a year in service and died, so we replaced it with a new plc of the same vintage (the serial is only 5 apart), and it died in about a week. So, both PLCs power up ok, but run is off and the err light is flashing. They won't communicate via USB nor serial, so I can't connect to see what's up. Is there a way to unbrick these given that they don't respond on the comms ports? Thanks!
Inntele Posted May 2, 2015 Report Posted May 2, 2015 Have you switched the PLC to Stop mode, before the attempts to get a communication? I suppose that it's not a problem with PLC hardware, but with PLC program code, which may be written incorrectly and due to it the PLC get overtime of its scan.
larry818 Posted May 2, 2015 Author Report Posted May 2, 2015 Yes, I tried switching to stop. Bear in mind that the code worked fine for a year and then it bricked. It's the same code I have running on a couple hundred installations, all with no problem. On site, it's connected to two FX2N-4DA modules, but those seem to be working. There's a third, new plc in place now that's working fine, no changed to code, config, nor wiring.
Inntele Posted May 3, 2015 Report Posted May 3, 2015 If a communication with PLC can not be achieved even in Stop mode, then I do not know a way how to make it alive. Sorry...
JRoss Posted May 4, 2015 Report Posted May 4, 2015 Try clearing the memory and put a one or two rung program in and see if it goes into run.
Inntele Posted May 4, 2015 Report Posted May 4, 2015 JRoss, How it can be done, if it's impossible to get any communication with PLC?
JRoss Posted May 4, 2015 Report Posted May 4, 2015 Ah yes, that would make it difficult... Have you contacted your distributor or Mitsubishi tech support?
larry818 Posted May 4, 2015 Author Report Posted May 4, 2015 That's another problem, my long-time local MEAU distributor is no longer an MEAU dist, and the new guys know nothing (and stock nothing). The MEAU tech support guy wanted me to send it to them, but I suspect that'd be a waste of the shipping fee.
Sergei Troizky Posted May 4, 2015 Report Posted May 4, 2015 (edited) I would try this by adding a RS-232 module or board. Edited May 4, 2015 by Sergei Troizky
larry818 Posted May 5, 2015 Author Report Posted May 5, 2015 Revisiting this, while these plcs look really clean inside, looking at them again under a powerful magnifier, I found corrosion everywhere. I suspect they got exposed to concentrated ammonia or chlorine gas. Thanks for your suggestions!
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