Mitsu Melsec FXN2 no run @ startup

[edgecrusher]

This is my first on the job exposure to messing about in a PLC with a PC. So far it hasn't gone too bad but I'm having a problem and it all started with a dead battery alarm. I wanted to backup the memory because I was getting an alarm that couldn't be cleared and the machine would not run with this alarm active. I successfully saved a copy with GX developer, but I found out my battery wasn't arriving today which was my deadline to get it running. I decided to try something I noticed while backing up.
In the parameters there's a selection for "Battery less mode". I figured maybe this would help me run the machine Monday without a battery but after creating a new project with this selected and writing it to the PLC I started having an issue with it not wanting to go into run mode after restoring power. The first time I tried to write to the PLC I did not put it in STOP with the little switch next to the DB9 plug. I got the warnings on the screen but just ok'ed my way through. I tried "verifying" and had some 23 differences in my device memory. Not sure what that means or even where to start with that information. Oh and the battery less mode did nothing to help me run it with no battery. But when I look at the screens everything looks to be in the PLC correctly. I figure there must be something I missed along the way.
So anyway where I'm at now is it won't just start running when powered up with the main switch. I am able to connect with the PC and using remote operation switch it to RUN mode. Obviously when the operator shuts it down at the end of the day I'm back to restarting it with a PC.

Just wondering what the possible causes for this can be. Honestly, I'm in a little over my head at this point but I'm the only one here that can figure it out. Any help would be great and hopefully point me in the right direction. I hope I don't sound like an idiot.

thanks in advance

P.S. I made a makeshift battery pack with two AA's soldered together making 3.2 out the 3.6V of the required backup battery's voltage rating and got the alarm to clear.

 

[Ronnie Sullivan]

Zip or rar your program and attach it to a post.
We can have a look at your settings.

 

[edgecrusher]

Zip or rar your program and attach it to a post.
We can have a look at your settings.

Here it is...

 

[Ronnie Sullivan]

Well, that was quick to diagnose

In parameters you have X0 set as a run terminal input.

Either you need to put a signal to X0 or delete that setting.

Looking at the program, there is no X0 in it or a high speed counter that could be attached to it.

You have either lost the X0 signal or accidentally made that a run signal.

 

[edgecrusher]

I believe that may have been something I had changed and forgotten about.

I appreciate the help. I'm in the last couple classes of my electrical maintenance technician degree. I'm currently in a control systems class which is kind of a primer for my PLC logic class next semester. So hopefully, in a few months I'll be able to look back at these mistakes and laugh.
I'm going to change that parameter and give it another shot. thanks again.

 

[edgecrusher]

Turns out the RUN/STOP switch was not making contact. I changed the parameters first but still no RUN. I started fiddling with the switch and noticed if I pushed it a little harder it went to run but was intermittent so it's probably got a bad solder joint or contact.

Thank you for the help.

Now I'm studying the program and wondering about the lack of comments. Is this something I can add to help make the program easier to follow? Is there any way to figure out what the original programmer intended each device name to be? I've been comparing it to the electrical schematics, but I don't see any correlation going on between the two regarding labels. I should probably just wait until I get my programming training, but I'm really curious how this all works. I'm assuming it's probably more than anyone can help me with in the limits of this thread.

 

[Ronnie Sullivan]

You can add all the comments you need.
The best way is to identify all the inputs you can. ie stop start auto etc by watching which input comes in from where.
Then the same with outputs.
The program will start to be a little clearer.
Monitor the program and work out which part does what and comment it.

 

[edgecrusher]

You can add all the comments you need.
The best way is to identify all the inputs you can. ie stop start auto etc by watching which input comes in from where.
Then the same with outputs.
The program will start to be a little clearer.
Monitor the program and work out which part does what and comment it.

I have just downloaded the programming manual to help me get familiar with the code and how it works.

 

[Ronnie Sullivan]

That's the best way.
I bought the hard copy programming book a long time ago.

It was pretty dog-eared after a year

 

[edgecrusher]

If I'm cutting my teeth on this Mitsubishi programming manual, how likely is it that it will help me down the road with other manufacturers? I've heard they all program different. I'm hoping learning on something a little older like this will make the newer stuff easier. Maybe just have to adjust for different procedures?? Tomatoe tomahtoe??
I'm really impressed with how easy to understand Mitsy made their manual. If only my some of my textbooks could be so well put together. I made it through basic devices yesterday and now I'm nuts deep in devices detail.