Troubleshooting tomorrow: Mitsubishi SEPLC AX2n-64MR, RTC Check

[AutomationTechBrian]

I was troubleshooting a customer's machine today, and I came across a couple of questions that I need your thoughts on.

1. At the end of the day, we came across an HMI screen that points to an "RTC Check" problem. I looked through the machine's manual to try to figure out what "RTC" stood for. Having a BIOS Check in the same list made me believe it referred to the only thing the HMI was connected... the Mitsubishi PLC (that has a different brand name). It wasn't anywhere in the manual, and it didn't occur to me what it was until I was driving home.... "Real Time Clock" I now presume.

2. I have very little experience with Mitsubishi PLCs, however I do have GX Works 3 on my laptop. I'm not sure why the Mitsubishi part number is on the PLC, but a different brand name, "Shihlin Electric" is on the PLC. After creating this post, I'll start looking for answers about that question, as well as the correct communication cable, in hopes that I'll have what is needed to connect tomorrow.

If you have any thoughts on either of these two questions, let me know. I'll put one picture in this post, and one in another post so they show up without opening the files.

 

[AutomationTechBrian]

And here is the PLC:

 

[lfe]

If something can cause a clock to lose the correct time, it is that the battery is exhausted.

Change the PLC battery

 

[parky]

It's a Taiwan clone, it is almost identical to the FX2N, however, some of these clones have small differences, some of the more open board types will not allow modifications to the PLC parameters, however, I do believe this version will allow it. your problem is almost certainly the RTC in the HMI & probably not in the PLC, it depends on the HMI but many have an RTC chip with built in battery (non replaceable), the chances are they are not really using it for any special purpose apart from displaying date/time, in saying that, I suppose it could be used for some sort of auto start or shutdown based on time of day but that is rare, Some HMI's do rely on a separate battery for the RTC usually a button type cell, I suggest if possible you upload a copy of the program in GXW3 you will need to start a GX Developer session in ladder Upload the PLC program, PLC Parameters & data table called "MAIN" (this will save the values currently in the Data memories). If it will not let you upload the PLC Parameters then this is because they are not changeable also, it may need your coms setting to 19200 baud, True Mitsubishi PLC's (when connecting via GX ide the IDE will interrogate the PLC & request it to communicate at the baud rate set in the IDE), however, although the programming port will always default to 9600 on a true FX, as stated some clones will only communicate at 19200.
Of course there is also the possibility that the PLC or HMI may have a password protection.
EDIT: for a true FX PLC the cable is a 422 so you will need a 232 (or USB) to 422 converter the Mitsubishi one is an SC09, however, cannot confirm that it will be 422 as a number of clones are 232.
Looking at the website it appears there are no PLC's as such anymore perhaps these were re-badged Mitsubishi products so could be true FX PLC's.

 

[AutomationTechBrian]

BTW... thanks for the info. I'm still working on this, although I no longer suspect the RTC issue is causing any problems. We worked on it today, and made some progress, but my contact had to leave early so we'll wait until after Christmas to continue.

I did some digging for info last night on the connection to the PLC. There is a guy who posts a lot of Mitsubishi info on another board who gives me the impression that my new software will have issues connecting to that old PLC. I haven't gotten to to point of needing to connect to the PLC yet. I like to use phone videos of the local I/O LEDs while the machine is running for troubleshooting because it's easier to see the connection of *all* the inputs to the outputs, then compare it to the same thing on a similar machine. Once that becomes a dead-end, I'll try getting into the PLC. It's not tag-based addressing, and there are no comments, so it's often a slow road to figuring out the issue that way.

As always, thanks for the info!

 

[parky]

If you have GXW-3 then when you create an FX Project it will run in GXW-2 compatible mode select ladder as the type, this works on all FX from 0-3U only not on the FX earlier models i.e. FX48MR, it should also come bundled with GXDeveloper.

 

[AutomationTechBrian]

I just have a minute...

This (link) is the kind of thing I'm seeing about compatibility. But, with that said, we all understand that you never know for sure until you actually try it.

 

[parky]

Yes that's right, As I posted, some clones only work at a particular baud rate so you may have to try all combinations (well usual ones).
I would also check if the programming port is 422 probably is but the HMI connection should confirm this.

 

[parky]

Another thought has occurred to me, if it is a rip off clone it could be using the old firmware i.e. FXxx & not the FX2xx, in this case then GXW or GXDev may not connect, you may need the older Medoc dos to connect. or possibly GXDeveloper but a very early version.

 

[goghie]

I'm still maintaining few Shinlins like that from picture, and they are all 100% compatible to Mitsu FX2N. Also used both SC-09 and FX-USB without problem.

 

[parky]

@ Goghie: That was my impression that it should be FX2N compatible, many are, do you know off hand if they are able to change baud rate like the FX2N?, I know some clones are not but most of them are the bare board ones.

 

[goghie]

It is rebadged Mitsubishi, it is not clone so they are able to change baud rate.