raspberry pi modbus slave

Question

Hello There,

Anyone Please help me with Modbus. I am completely new with modbus

I am Stuck here. I have to make my Raspberry pi as slave device which will response to modscan32 software.

Currently i am using libmodbus stack, but it constantly popping the error that "modbus.h, no such file or directory."

I am using RX TX gpio pins for Data Transmitting and receiving along with RS232 circuitry.

Please suggest me if any alternative modbus libraries available for raspberry pi.

thank you.

luislabmo · Answer

Hello patil.sunny9999 , try these instructions https://github.com/stephane/libmodbus/wiki/Libmodbus-on-Raspberry-pi Good luck!

rew · Answer

That means that the compilation requires a file called "modbus.h". That would be something that comes with a modbus library. So you type: apt-cache search modbus This looks for packages wtih "modubs" in the name. You will see "libmodubs" and libnmodubs-dev. ThThe first one is the run-time, that people running things that use the lib need, the second one will have development files that you need. Sorry for the typos. Element14 has changed the forum somehow to scroll to the top of the topic for every character that I type. Interesting way to allow peopel eto eneter stuff into a form....

rew · Answer

There are two possibilities. First, there is a / missing in /dev/ttyAMA0 .

Second, you may have a raspberry pi 3, where ttyAMA is used to communicate with the bluetooth. I'm not sure what the best option would be, but the first thing to try is to activate the disable-bt overlay: Add to /.boot/config.txt:

# Disable internal BT dtoverlay=pi3-disable-bt

P.S. The new "scroll to top of thread" that happens when you press a key while editing a post is highly annoying. I had to finish typing this blind.

rew · Answer

May I refer you to my post above. It gives you the answer.

rew · Answer

It will be in /dev, but not in dev. The configured device name is wrong. Simple as that. Now we have the full error message it is clear as crystal: There is a typo in the confgured devicename. without the error message we were left guessing if there was a typo in the transcript from the error message, or if there was something else going on. With the full error message, there is a very small chance that he typed it all by hand, and the same device-name-with-typo is mentioned twice in the error message. There is no doubt about it. Peter, the error message is: "no such file or directory". So it is NOT a permissions problem. Apparently people have trouble with "it could be this, or it could be that". Then when it turns out it is not "this", then the "that" option should be investigated. By suggesting a permissions problem, that cannot be the cause, you risk patil going off on a wild goose chase again.