raspberry pi modbus slave

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

Good luck!

dhruvvyas90 i am using your libmodbus-master stack for RPi test. as i compile test.c from Rpi-test folder it gives me following error

" test.c:10:20: fatal error: modbus.h: No such file or directory "

Please help me out I am beginner with linux and raspberry pi.

Thank you in advance

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....

dhruvvyas90 rew As i Come out of one Error, I messed with Another one. please suggest me any solution for below error.

pi@raspberrypi:~/libmodbus-master/rpi-test $ gcc test.c -o test `pkg-config --libs --cflags libmodbus`

test.c: In function ‘main’:

test.c:45:5: warning: implicit declaration of function ‘modbus_enable_rpi’ [-Wimplicit-function-declaration]

     modbus_enable_rpi(ctx,TRUE);

     ^~~~~~~~~~~~~~~~~

test.c:46:5: warning: implicit declaration of function ‘modbus_configure_rpi_bcm_pin’ [-Wimplicit-function-declaration]

     modbus_configure_rpi_bcm_pin(ctx,BCM_PIN_NO);

     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~

test.c:47:5: warning: implicit declaration of function ‘modbus_rpi_pin_export_direction’ [-Wimplicit-function-declaration]

     modbus_rpi_pin_export_direction(ctx);

     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

test.c:62:5: warning: implicit declaration of function ‘modbus_rpi_pin_unexport_direction’ [-Wimplicit-function-declaration]

     modbus_rpi_pin_unexport_direction(ctx);

     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

/tmp/ccorPCkV.o: In function `main':

test.c:(.text+0xc8): undefined reference to `modbus_enable_rpi'

test.c:(.text+0xd4): undefined reference to `modbus_configure_rpi_bcm_pin'

test.c:(.text+0xdc): undefined reference to `modbus_rpi_pin_export_direction'

test.c:(.text+0x19c): undefined reference to `modbus_rpi_pin_unexport_direction'

collect2: error: ld returned 1 exit status

rew Robert Peter Oakes The specified item was not found. @

hello there.

can any one please help me with this.

SerialException: [Errno 2] could not open port dev/ttyAMA0: [Errno 2] No such file or directory: 'dev/ttyAMA0'

i search alot but cannot find the proper solution for it.

i am using Raspberry pi 3.

thank you in advance

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

i have already disabled the bluetooth, and my serial communication is working properly too.

as i run my pymodbus server program it shows me that error

the complete error it show is as below.

INFO:pymodbus.server.async:Starting Modbus Serial Server on dev/ttyAMA0

Traceback (most recent call last):

  File "/home/pi/pymodbus-master/examples/common/callback-server.py", line 134, in <module>

    StartSerialServer(context, identity=identity, port = 'dev/ttyAMA0')

  File "/home/pi/.local/lib/python2.7/site-packages/pymodbus/server/async.py", line 272, in StartSerialServer

    SerialPort(protocol, port, reactor, baudrate)

  File "/home/pi/.local/lib/python2.7/site-packages/twisted/internet/_posixserialport.py", line 37, in __init__

    xonxoff=xonxoff, rtscts=rtscts)

  File "/home/pi/.local/lib/python2.7/site-packages/serial/serialutil.py", line 240, in __init__

    self.open()

  File "/home/pi/.local/lib/python2.7/site-packages/serial/serialposix.py", line 268, in open

    raise SerialException(msg.errno, "could not open port {}: {}".format(self._port, msg))

SerialException: [Errno 2] could not open port dev/ttyAMA0: [Errno 2] No such file or directory: 'dev/ttyAMA0'

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

Have you enabled it through raspi-config and possibly given yourself permissions if your not running as root ?

Also look in /dev you should see a file called ttyAMA

hope this helps

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.