MC Protocol PLC Side Settings for FX5U

@Steve-Mcl, I see that you are the author of the MC Protocol flow. I am new to node red, but I see that you are pretty responsive in this forum and I have read through your posts on connecting to other mitsi plcs but I am a bit confused on setting up my PLC from GXworks3 for MC... I dont have the same options as you showed in your working examples.

This is what I have here... The first 2 melsoft connection modules are GOT HMIs, and the 3rd and 4th connections are my attempts at trying to follow your guidance. Am I completely off track here? I could not find this screen so I assumed it was an older version of gx works

I see that you recommend setting MC protocol to UDP, but that is not available to be changed in this window. Can you point me to the correct menu if I am in the wrong one?

According to this SLMP is QnA 3E or 4E compatible …

The message format of SLMP 3E or 4E frame is the same as the QnA-compatible 3E or 4E frame in MC protocol. The correspondence table of MC protocol and SLMP is shown below. When connecting an external device which uses MC protocol to an SLMP-compatible device, check if replacement of command is required.

So try setting the port to SLMP, 4E, UDP and apply similar settings on the node.

Please let me know how you get on.


PS, another user confirmed operation with FX3U however I would only recommend that if SLMP 4E or 3E doesnt work.

Upon reading the FX5U spec I believe the only supported formats are 3E so I will give it a shot this afternoon.
I dont understand the differences between SLMP and MC commands/frames. So I'm assuming i may run into some trouble there

I was actually able to read and write to some registers via a raspberry pi using TCP 3E SLMP frames. Thank you so much for your flow and active assistance :slight_smile:

I strongly recommend UDP if you want reliability. Mitsi Ethernet TCP ports are (in my experience) VERY poor/prone to lock ups requiring a physical PLC power cycle to recover them. UDP is much more reliable.