Problem with transition from Mitsubishi A to L series

[gurar]

I have gotten help with some issues in the past on this forum, and I'm hoping someone can help me again. My company is an OEM that used the Mitsubishi A-series PLC with several Beijer HMIs in a portable industrial machine for over 20 years. This machine may be stored without power for months at a time. Thus, neglecting to change the PLC battery prior to its expiration causes headaches- loss of machine data as well as the operating software. In those cases, I reload the software with Medoc, E-Designer, and I-Designer software. I'm not a programmer; reloads are one of many customer support functions I have to keep the machines running.

Also, we have had software upgrades from time to time and I have tried to get these installed on as many machines as possible, one way or another. During the upgrades, the machine's test data was not affected. I presume it had been stored in a different memory area.

We transitioned to the L-series a few years ago and our software engineer rewrote the machine's control program. He retired soon after the transition and sadly passed not long afterward. So, that knowledge base is gone. When some changes had to be made to the new software, I noticed a few things that our other software engineers have not been able to figure out.

• I experimented with removing the PLC battery for a week or so with power off and found that none of the software was affected, only the PLC clock.
  
• When new software is loaded to the L-CPU via the SD card, it wipes out all of the customer data as well. We've had some folks speak with Mitsubishi, but nothing has come of it.

So I have a few questions.

1. Is it possible to allocate the information stored in the CPU so that an intentional replacement of some (the control software) does not affect other information (end user's test settings and results)? If so, would that require a major change to our software, or would a few memory addresses just need changing?
2. Our system clock was at one time kept by the HMI, but then it was changed to the PLC, and now it is back in the HMI (Beijer X2 Base). This, and my battery experiment makes me believe the PLC battery has no real function in our machine now. Would that be true?
3. I would like to change the system clock back to the PLC because it seems to have a much simpler battery change procedure. I'm thinking this should be a simple change, but I really don't know. I recall the Designer programs have checkboxes for system clock, but maybe it is more complicated than that?

Thank you.

 

[parky]

Never used the L controller but my guess is that loading the program from the SD card it copies the data memory areas from the card, or possibly resets them, again I have never used an SD card to restore a program so not sure.
I bet if the data memory is stored on the SD then it probably is all clear i.e. not taken from the PLC.
There are a couple of things i.e. A & Q series, many people forget to back up data i.e. "D" registers etc. also there are file memories "R" registers, I always take a backup of the main memory areas to my file when the machine is not running i.e. PLC in run mode but at a standstill.
Another problem is the PLC parameters, in there the latch range for memory can be set for example initially it might be configured for example "D" memory latch range of 500 to 1024, the range for latching (retentive) can be changed, many programmers forget to download the configuration when fitting a new processor & the backup of the last state of the memory areas.