Sign in to follow this  
Followers 0
SimonA

Q03UDE PC to Built-in Ethernet port comms (MC Protocol)

8 posts in this topic

Hi, We want to communicate from a PC to the PLC using MC Protocol over TCP/IP with a 3E ASCII Frame, but we are not having much success. We can connect over TCP/IP but cannot get any response from the PLC with the frames we are building based on the manual: Q-L_UserManual-MELSEC-CommunicationProtocol-ReferenceManual_SH_080008-Q.pdf Please, can anyone offer a little advice: Q1 - What are the settings in the PLC for the built-in Ethernet port (We have port 1026 listening using MC protocol) Q2 - An example of any ASCII frame that should get a response from the PLC Many thanks, Simon.

Share this post


Link to post
Share on other sites
Built in port does socket communication not MC. See the right manual for the Q with built-in Ethernet. Mitsubishi has many example programs for how to communicate with either E71 module or built-in Ethernet. Check their website. SH(NA)080811

Share this post


Link to post
Share on other sites
See chapter 5 in this manual. You need to define "MC Protocol" in your port settings and binary/ascii (depending on what you use) in your Q parameter settings. If you're not sure about your 3E frame, you can try with the much more simple 1E frame to test (is only available in some of the newer QnU cpu's though, see appendices). There seems to be some limitations to the MC protocol commands you can use in QnU compared to dedicated ethernet cards. Edited by Mitsu

Share this post


Link to post
Share on other sites
Many thanks for the reply Crossbow, We have had socket communication working on the built-in port but we want to go MC. I am a little confused that you say the built in Ethernet port does not support MC protocol, Am I misunderstanding you? If you are correct then that may well be our problem! but the manual (SH(NA)080811) seems to say otherwise: On page A-9 it says that it covers the Q03UDE (our PLC) On page 3-1 the diagram and table lists MC Protocol as a supported function of the built-in Ethernet port On page 3-14 there is a section 3.3 MC Protocol Communication - this covers set-up of the MC Protocol on the built-in Ethernet port. I've been using the manual "Q-L_UserManual-MELSEC-CommunicationProtocol-ReferenceManual_SH_080008-Q" which describes the frame structure that is not working for us. (3E ASCII). It describes a frame header (Section 3.1.2) but never defines it's content, which is something that could be a problem? (I'm not refering to subheader). Maybe there is something better on the web site. Si.

Share this post


Link to post
Share on other sites
Thanks Mitsu, That's exactly how we have it set up, but try as we might, we have never had the slightest reply from the PLC. Which is why we think the frame may be wrong. If you have simple example of an ASCII 3E or 1E frame then I can try it right now (I assume there is no setting for the frame type) si.

Share this post


Link to post
Share on other sites
Indeed, there is no setting for the frame type necessary. The Mitsubishi ethernet card (in this case the QnU) will analyse the data it receives and if it matches a frame that it knows (in case of QnU 3E and 1E but 1E only from a certain firmware version since it was added later on), it will automatically send back a reply (which is the nice thing about MC Protocol: you only need to program communication on one side). You do seem to have the TCP connection succesfully opened with that particular port? The frame does need to be correct ofcourse or otherwise the card will not respond. I think we did approach a QnU with the 1E frame at some point but i can't check at the moment. Have you defined the actual command (e.g. i want to batch read 10 words starting from D0)? In this manual, the frame layout is described for several different commands. See chapter 3.3 for the defintion of the commands and examples. Edited by Mitsu

Share this post


Link to post
Share on other sites
As the other point out, there should be no problem. I see several people have linked to documents, but it would also be helpful if you could share some of your work until now for us to analyze.... What have you done so far? In what program/language? Can you share any code or is that out of the question? Can you share e.g. Wireshark logs to/from the Q?

Share this post


Link to post
Share on other sites
I was too brief in my reply. It supports MC Protocol, but only the one frame type. E71 modules offered a couple frame types.

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
Sign in to follow this  
Followers 0