Welcome to ModbusSniffer Discussions!

[snhobbs]

👋 Welcome!

We’re using Discussions as a place to connect with other members of our community. We hope that you:

• Ask questions you’re wondering about.
• Share ideas.
• Engage with other community members.
• Welcome others and are open-minded. Remember that this is a community we
  build together 💪.

To get started, comment below with an introduction of yourself and tell us about what you do with this community.

[PerfoPerfo]

Hello, This is perfect for what I've been looking for thanks. I have no documentation on a Modbus device I've got though it is communicating fine between it and the master. Am I right in thinking as my Modbus is rs485 I need an rs485 to usb converter then wire the rs485 end of the converter to the slave A and B terminals (i.e. in parallel with the existing link). I can then run this on the windows machine and see the traffic being sent back and forth between the master and slave ?

[snhobbs]

If your device has an A/B as the serial names then it's almost guaranteed to be half duplex RS-485 like you say. This lib will work but I would recommend getting a cheap logic analyzer and using the modbus decoder stacks with pulseview/sigrok. Here's a blog post on doing that: https://www.maskset.net/blog/2022/10/13/sigrok--10-logic-analyzer/

You can also use an ftdi usb-rs485 based dongle with pulseview/sigrok.

[PerfoPerfo]

Thanks for the reply. Using the logic analyser can I see the commands in print ? Ie not just the binary train ? Why do you think this will be better than your lib ? I haven’t got the hardware yet so could order either or both…. Thanks again