Modicon 984-455 loses run & ready light

aaronhigg

Member
Join Date
Dec 2004
Posts
1
I have a Modicon 984-455 which is giving me problems. Without any reason or warngin it loses it run and ready light. To get it going again you have to cycle the power and start it again with the laptop. Sometimes it does it once a week sometimes it does it once a week, sometimes once a day, sometimes once an hour. I have checked the input power with a voltage recorder and it is constant. What else is there to check? After you lose the ready light you cannot connect with the laptop until you cycle the power. Then you get a stop code of 0200. Is there anyone that has encountered this problem before..... HELP!!!

Has anyone had this type of problem with recently purhcased Modicon 984's???
 
Last edited:
I do not recognize the processor 984-455. Is this the obsolete replacement unit that could be mounted in an old 484 chassis?

Does the processor lose it's memory (i.e. dim awarness) or does it only lock-up?

Rarely do CPUs fail intermittently. It sounds like you have a bad power supply, rack/chassis assembly, or an I/O card that is failing. I would start with investigating the power supply.
 
Hi
If your supply and rack are OK try clear the logic in plc ( remove the power off the plc and then remove the batery) and download your program again.
Regards
Andrzej
www.modbus.pl
 
stop code 0200

A few years back had intermittent 0200 stop code faults on a Modicon micro that was used on a Caterpillar Loader. Had to logon with laptop and start controller. Eventually found vibration causing bad ground on powersupply. Reterminated and problem went away. (At least that's what the technician told me.)

Brian.
 

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