Jump to content

TCP Modbus + nModbus

Recommended Posts

Hi there

I'm working on a project for UNI. My basic goal is to read data off Ethernet enabled Vision V130 via Modbus, using C# nModbus library.

PLC is configured, following example from VisiLogic help, to act as TPC Modbus slave, while custom software on PC. acting like Modbus master, takes care of data reading. I managed to get everything working. I could see coil states and 16/32-bit register values on my PC. So far so good. Problems started when I upgraded VisiLogic to the latest version (8.6.1) and with it, PLC's O/S. From that point on, I couldn't read anything anymore. Debug showed "null" as read value. My best guess is that something has changed in PLC's Modbus message structure, which made it incompatible with nModbus. Both, PLC and PC programs stayed the same.

I read change logs and noticed few changes regarding Modbus, but I can't tell if that's the cause. That's why I'm turning on you for help.

Thanks, Wisse.

Old (working) version:

VisiLogic 8.0.1 Build 0, PLC: V130-33-R2(A), O/S: 3.0(09), Boot: 2.1(01), Factory boot: 1.1(00)

New (not working for me) version:

VisiLogic 8.6.1 Build 0, PLC: V130-33-R2(A), O/S: 3.1(19), Boot: 2.2(02), Factory boot: 1.1(00)

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...