Modbus Protocol on Raspberry Pi 3 using Serial GPIO Ports

Hi there, I have a better suggestion , try using Node-Red and the Modbus plugin, if you are a beginner then this I think will be an easier route to go, I have loads of Node-Red videos on my channel and alot of them use Modbus to talk to a thermal imaging camera and other devices

Node Red is included with the Raspberry PI image and it is easy to add the Modbus plugin right from within Node-Red UI, look for the pallet manager. The plugin makes it so much easier to talk to modbus devices and node-red will allow easily to configure workflows and displays without the need for extensive coding. You can code stuff if you want but I would suggest getting to know Modbus first and then go from there.

If you need help with Modbus I can help, I just have never needed to use the python interfaces.

Regards

peter

Oh, my channel is https://www.youtube.com/thebreadboardca

If necessary i will create a video for E14 and post it here to help, I have many devices I can choose from

Sorry, missed the other part of your question, the, an Arduino may make a better Slave device and there is a sketch for that, just search for Arduino and Modbus.

Is there a reason you have to use MODSCAN 32, this seems to be more of a debug tool, it this an assignment or something, perhaps you can provide a little background info so others can also help

Robert Peter Oakes Yes, actually its my Project. so I have to use it on Modbscan 32 only. I want to run it on Raspberry Pi though.

If possible for you Please make Video on Raspberry Pi  as slave communicating with Modscan 32. it will help me alot

Thank you.

Hey There,

I am using Libmodbus Library for my Raspberry Pi as Slave Device, but i am stuck on following error

slave_c.c:9:20: fatal error: modbus.h: No such file or directory

here i am using simple test program from libmodbus examples

Anyone please suggest me how to overcome this problem

thank you in advance

I'm not familiar with the modbus libraries, but that is just a typical c compiler error when it can't find an include file. Either you didn't install the modbus package as directed, or they left out an instruction.

you can add the -I command line option to tell the compiler where to find the directory where the include file is located. See the following.

https://gcc.gnu.org/onlinedocs/gcc-3.1/gcc/Directory-Options.html

Mike

Hi Peter

i have been using a raspberry pi and node red for modbus communications with PLCs for a while now, but I have only ever done it over TCP modbus.

I now need to do the same but over modbus serial, we are trying not to use a hat as we might want them in future for other reasons.

so that means I really need to use a USB modbus plug in device which I have various. I just can’t seem to set up the pi and node red to read modbus  through the USB adaptor.

Please anyone who has done this successfuly before HELP.