Mitsubishu FX2N-48MR Issue upon power down

checdw · Aug 29, 2013

As anybody gone through a situation on where you power down your equipment afternoon one day and next day morning that you power up the equipment you start having PLC issues, like the DC outputs not working correctly and after 2 hours everything start working as usual?.

I only though that possible if there were battery issues but the Indicator of this situation is not lit at all. What else could it be, now I need to leave the machine on all night just so that we can start next day without a issue.

The PLC is a FX2N-48MR with two DC expansion Modules and a Pulse generator module, the PLC has a EEPROM 4.

Any thoughts, should I proceed and change the battery just in case?.

Sincerely
Edgar C.

iant · Aug 29, 2013

I would think that the pulse generator control may need homing.

checdw · Aug 29, 2013

iant, but the driver works correctly the issue become the DC inputs on the main PLC and the expansion card, they tend to not change state even that you measure and have the correct level of voltage and you could also see the LED indicator of the input being present or not, but on the ladder program under monitor de Input doesn´t change state. So all this week we have left the machine power up all night even that is not being used, but tomorrow Friday we will shut it down since the 2 day weekend is higher the risk of something happening.

iant · Aug 29, 2013

If the input is not working then posibly that is the problem
The Mits PLC's have plug in screw terminals maybe there is a fault there and it is not making contact.

checdw · Aug 30, 2013

Iant, Yes the input doesn´t seems to respond to the change of the electrical state, but after 2 hours of being rebooting the system it suddenly start to work, we even tested the theory and have not power down the machine the last 3 days and we have not had a issue, but this weekend we have to power down. So we will see next Monday if we see this same situation. By the way we have check all terminal connections and Power levels just to be sure it was nothing like this the problem.

Sincerely
Edgar C.

iant · Aug 30, 2013

what is the LED status of the PLC
And
please measure and confirm the 24Vdc supply.

Does this unit has an EEprom?
Also check all other power sources on the machine.
- Might not be related but I have had a fault on a 3 phase transformer on one machine - Opposite effect though - drops out power when loaded.

checdw · Sep 2, 2013

Iant,

The led status are Power and Run both green and always lit, the rest are off (Battery and Prog-E/ CPU-E).

Yes it does have a FX-EEprom-4.
I have check all the power sources and they are at the correct levels.

I have ordered the backup battery to exchange just in case.

iant · Sep 2, 2013

what is the actual voltage - please measure
the green light has nothing to do with the voltages

keithkyll · Sep 2, 2013

This is classic power supply Electrolytic caps. If it's a linear, check the cap(s) to see if it's hot. If it's a switch mode (SMPS), look to see if the caps have expanded tops, or are burning plastic label, etc.
You need a 'scope to measure 50 KHz ripple.
Try replacing DC supplies temporarily, just to see if this is it.
Also check PLC power supply. Same reason - caps.

iant · Sep 2, 2013

I have had a fault where the Green light was on but the inputs would not work and the HMI was flickering.
The green light is the 5v Dc rail from the processor
it has nothing to do with the 24v DC supply
So it can misslead you to the cause of the fault

checdw · Sep 3, 2013

Keithkyll, Iant,

I have tested with a separate power supply because we did also thought that maybe noise on the power supply was the culprit, but we saw the exact same situation, also as mention previously this failure has only happen upon powering down the system once the machine as been power up for at least 2 hours it work perfectly, and since last week we are not powering down the machine an no failure has happen since, so if there were any other power supply issue you will not make it work so I think it will be safe to conclude that the issue is not related to the power supply either the +5 or the +24 VCD.

Sincerely
Edgar C.

James Mcquade · Sep 3, 2013

checdw,
have you checked your control wiring?
sounds like you may have an on delay timer set for 2 hours rather than 2 minutes? once the on delay timer is done, the contact closes and provides power to the inputs or input common.

regards,
james

iant · Sep 4, 2013

could you zip a copy of your program (GX developer is what I Have)
I would like to look at it

checdw · Sep 4, 2013

James Mcquade said:
checdw,
have you checked your control wiring?
sounds like you may have an on delay timer set for 2 hours rather than 2 minutes? once the on delay timer is done, the contact closes and provides power to the inputs or input common.

regards,
james

James,

Yes we have check the control wiring, it would be something similar to the power check if something were wrong with the wiring the machine would not work continuosly after the 2 hours.

The machine doesn´s have any on delay or even off delay on the program, also if this were the situation you would not see the state of the input change measuring with the multimeter.

Tahnk you for the ideas.
Sincerely
Edgar C.

checdw · Sep 4, 2013

Ian, yeah sure I will try and send you a zip of the actual program, I need to figure out if I can share the file trough this fórum or do I need to send it trough a email or soemthing else.

The 2 hours is not a exact number it varies over time, we have seen taking from 15 minutes to up to 2 hours for the machine to work perfectly, and adter that it work the rest of the 9.5 hrs without any control issue at all.

Edgar

Sincerely

Mitsubishu FX2N-48MR Issue upon power down

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