Can FX3U device values be viewed offline?

4 posts in this topic

I'm attempting to look at an offline PLC program to see device values (Ts, Ds, Ms). Is this even possible? Are device values saved when saving a program online?

Program is for a Mitsubishi FX3U. Using GX Works2 v1.601B. Win10-Pro OS on the computer.

I've an AB background (several decades), but only a couple weeks with Mitsu. Unfortunately, the person who originally wrote and maintained these programs isn't available.

This is an easy process with AB, but I just hit walls in the Mitsu IDE. Can anybody help?

Share this post

Link to post
Share on other sites

Yes, go to Online - Monitor - Device/Buffer Memory Batch

Once opened, put the head address of what you want to view.


Hope this helps,


Share this post

Link to post
Share on other sites

Dave (plcdp), thank you for your response but it isn't working for me. I use the following steps:

1) Go online with the PLC and save the program.

2) Close the program and the GX Works2 IDE.

3) Unplug the programming cable.

4) Start up GX Works2 IDE and load the saved program.

5) "Online>>Monitor>>Device/Buffer Memory Batch" generates a problem dialog box: "MELSOFT Application - An unusable COM port was specified. Execute again after checking the COM port setting. <ES:01808009>"

I am unable (in this case) to be connected to the target PLC, but still want to see what the device values were the last time the program was saved.

Any other ideas? And thank you everyone for your time with this!


Share this post

Link to post
Share on other sites

RESOLVED. See below.

I called Mitsubishi tech support and, with Mitsubishi Mark's help, have resolved this. Below are the steps I used to view device values in an offline PLC program.

I'm not sure that all steps below are necessary, or if there might be short cuts, but these are none-the-less the steps I used. Efficiency suggestions would be appreciated.

  1. Connect to the PLC with GX Works2.
  2. Menu: "Online>>Read from PLC..."
    1. Click "Select All" button. (Probably only need to check the "Device Memory" check boxes in the "Module Data" area. But I clicked the "Select All" button; Mitsu newby attitude to cover myself.)
    2. Click "Execute" button. If dialog boxes pup up, accept them all. When done, click the "Close" button.
  3. Unplug from PLC, just to prove the point.
  4. Double-click in Navigation pane Project>>Device Memory>>MAIN. A spreadsheet-like presentation is opened in a "Device Memory MAIN" tab in the main window. In the "Column Selection" dialog box that popped up, I accepted the "Auto" default and clicked "OK". A spreadsheet-like presentation is provided with values for the various devices.
    1. At this point, we may want to select what particular device values we want to observe rather than scrolling through all the rows, and may want to change the format of the value display. Right-click the top-left cell of the spreadsheet-like presentation and click on "Input Device..."
    2. For my use, I did: "Device: Y", "Range>>Address: 0 to 27", "Display Mode: BIN", "Register: 16-bit", then clicked the "OK" button.
    3. Then, I added to the display by going through the "right-click>>Input Device..." again: "Device: D", "Range>>Address: 0 to 7", "Display Mode: Dec", "Register: 32-bit", then clicked the "OK" button.

I now have a display that shows the Y outputs and the D register values I want to observe at the top of the spreadsheet-like presentation.

Caveats: I do not know how quickly the device values are saved, so the complete device value set may be skewed in time. This would be best done with a PLC program that was not changing any values for the duration of the transfer of values from PLC to PC.


Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now