PLC with no output whatsoever

[Susovit]

I have a Mitsubishi PLC with transistor type output. The problem is that none of the output is turning on, not only output. The output indicator LEDs aren't showing up too. There error led is not glowing. What can be the problem. I know it the plc has a output side hardware problem because the software is showing the proper outputs. What can be the culprit.?
Please help

[R-1125F]

What is the model number and what testing have you done?

[coromonadalix]

was it working before or it is a replacement ??

[Susovit]

It is a Mitsubishi Fx3SA mt.it was working fine few days ago.
I accepts input. Input LEDs light on as I give input. The hmi shows the proper outputs when I test it in manual mode. The output LEDs and the outputs however doesnt work at all.

[JimmyJo]

Have you opened it? It's not uncommon for PLCs to have input output sections individually fused.

[R-1125F]

See if the fuses are good.   
Also, have you checked it using the PC software?

[BMK]

Please clarify..

Are the LEDs for the outputs not turning on?

On that model, the LEDs are on the logic board. The IO board is separate PCB. Very unlikely that a hardware problem or fuse on the IO board could result in LEDs off. If you have no LED, then your user program is not trying to turn on the output.... There are 2 likely possibilities..

1) An MCR instruction in the program is denying outputs. Usually as a safety measure. Check all inputs, especially those related to stop buttons/interlocks etc..
2) Program is lost. Yes, the Run light will happily light up if user program is empty...

Do you have programming software, or do you rely only on the HMI?

 

[Susovit]

I relied completely on HMI. The software could not be accessed due to password lock.
The plc had a blown power supply side when I checked. Output lights are not turning on. 
Run light is coming. Due to password, I think program is ok.
I have attached some photos.

[Susovit]

See if the fuses are good.   
Also, have you checked it using the PC software?

I think the output section is completely out. Can that be possible without the CPU being damaged?

[Susovit]

I think output side is damaged but can't trace how.

[Susovit]

I have used manual mode to turn on individual outputs from hmi. But the plc output LEDs won't come on. However, the hmi displays on properly.

[coromonadalix]

not sure if its them

But  some plc  even with the software have an hidden memory range / section,   the programation goes in there and will ne be accessible for retrieval,  even with a password  ...

had a similar one in a pcb oven, and for sure the maker re-sold them to us at twice the price, still not aceessible by any means


the plc may have suffered more damages than you think,  maybe its time  to change it, and yeah  you face the programming problem

is your equipment serviceable ?  suppport tech ?

[R-1125F]

Check the basics.  See if there is 24v and 5V measured on the output board.

[BMK]

I have used manual mode to turn on individual outputs from hmi. But the plc output LEDs won't come on. However, the hmi displays on properly.

This really tells you nothing. Depends entirely how the machine builder programmed it.. HMiI buttons likely just linked to memory bits. I strongly suspect you have lost the user program.

To rule out hardware problems on the PSU/IO board, you can swap logic board into new PLC.

Password on these is easily defeated by monitoring serial Comms on the login process. The password is sent plaintext  from the PLC to the programming software. The check happens at the PC side!

[BMK]

Damn, I'm old. I had to resort to the waybackmachine to get this:

https://web.archive.org/web/20050118130110/http://freespace.virgin.net/ian.sullivan/mitsubishi.pdf

Simpler times.

[coromonadalix]

ill be da....  loll


just found this forum, but have very old threads and recents

http://plcforum.uz.ua