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epsilonrt / mbpoll

command line utility to communicate with ModBus slave (RTU or TCP)
https://epsilonrt.fr
GNU General Public License v3.0
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mbpoll to simulate a Modbus slave? #8

Closed mmalyj closed 6 years ago

mmalyj commented 6 years ago

I would like to use mbpoll in place of ModbusPal as a Modbus slave simulator for testing purposes. Is that possible? ModbusPal is GUI based, but my lightweight Ubuntu 16 Core OS does not allow GUI, which is why I like mbpoll since it runs from the command line. But when I try to simulate slave 1 writing value 42 to register 2 :

$ mbpoll -m tcp -p 502 -a 1 -r 2 -v 127.0.0.1 42 #port 502, slave 1, start reference aka register 2, value 42, verbose, generated from localhost

I get the error

mbpoll: Connection failed: Connection refused

I thought mbpoll could simulate a slave, because the output from it says "mbpoll 0.1-23 - FieldTalk(tm) Modbus(R) Master Simulator". Please tell me what command line parameters I should use. Thanks!

mmalyj commented 6 years ago

I get it, mbpoll is a Modbus MASTER simulator.

EpsilonRT, do you have a similar Modbus SLAVE Simulator that can be run from the command line? I need to specify TCP, and even if it simulates just one slave and a value for one register, that would be adequate.

epsilonrt commented 6 years ago

Hi, mbpoll is indeed a master. I do not know any slave "open source" but libmosbus also allows to design MODBUS servers (http://libmodbus.org/docs/v3.1.4/). You have this project https://github.com/taka-wang/c-modbus-slave/blob/master/src/server.c that could allow you to simulate a simple slave. I do not need this feature in my work, so for now, it is not planned to integrate with mbpoll. regards.