libmodbus

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Welcome to the libmodbus list.

Before posting, take time to clearly explain your problem and don't forget to read the documentation on the website http://libmodbus.org.

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Mar 17

Relative Addressing functionality?

Good day All, You can ignore my previous post, as I reviewed the source code and it does not appear

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Relative Addressing functionality?

Good day All, You can ignore my previous post, as I reviewed the source code and it does not appear

Mar 17

Jan 19

mb_mapping types unnecessarily signed

This is a very minor problem, but while going through some compiler warnings, I noticed that the

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mb_mapping types unnecessarily signed

This is a very minor problem, but while going through some compiler warnings, I noticed that the

Jan 19

Jan 13

Support for Function Code 08 in libmodbus | Diagnostic counters

Hello, I have a requirement in my project where I need to read the diagnostic counters and I see

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Support for Function Code 08 in libmodbus | Diagnostic counters

Hello, I have a requirement in my project where I need to read the diagnostic counters and I see

Jan 13

12/15/22

modbus over UDP

Hello. I found one old attempt to make UDP transport in this library: Old Attempt but it was not

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modbus over UDP

Hello. I found one old attempt to make UDP transport in this library: Old Attempt but it was not

12/15/22

Cédric Boudinet

11/2/22

How to detect holding registers writing queries

Hello I am developing a modbus/TCP server using libmodbus v3.1.6. Since there is no callback system

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How to detect holding registers writing queries

Hello I am developing a modbus/TCP server using libmodbus v3.1.6. Since there is no callback system

11/2/22

11/1/22

Modbus RTU Server with multiple slaves

Hello, I want to create a simulator like ModRSsim2 https://sourceforge.net/projects/modrssim2/ I

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Modbus RTU Server with multiple slaves

Hello, I want to create a simulator like ModRSsim2 https://sourceforge.net/projects/modrssim2/ I

11/1/22

Sangeetha Elumalai, ZipperSnake5

10/25/22

unit test server return ERROR Connection reset by peer: read

Hi Hans, There is no failure in the test cases?? Is this expected log?? Kindly clarify my doubts.

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unit test server return ERROR Connection reset by peer: read

Hi Hans, There is no failure in the test cases?? Is this expected log?? Kindly clarify my doubts.

10/25/22

Stéphane Raimbault, Rick6

8/22/22

New release of libmodbus v3.1.8

Fair enough. > On Aug 22, 2022, at 12:54 , Stéphane Raimbault <stephane....@gmail.com>

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New release of libmodbus v3.1.8

Fair enough. > On Aug 22, 2022, at 12:54 , Stéphane Raimbault <stephane....@gmail.com>

8/22/22

8/7/22

modbus inter-frame timing

I've been investigating an issue wherein I get a lot of timeouts from my devices. I finally

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modbus inter-frame timing

I've been investigating an issue wherein I get a lot of timeouts from my devices. I finally

8/7/22

7/14/22

"Response not from requested slave"

Hello all, I am creating an application on a PC, using an RS485 USB dongle. I have only one device

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"Response not from requested slave"

Hello all, I am creating an application on a PC, using an RS485 USB dongle. I have only one device

7/14/22

Bernat Sanchez Muñoz

7/1/22

Problem with compile library that it didn't happen before

Hi, Not the first time that I used this library and I installed in other pc two weeks ago but today I

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Problem with compile library that it didn't happen before

Hi, Not the first time that I used this library and I installed in other pc two weeks ago but today I

7/1/22

6/22/22

Filter messages by slave address

Hello. Just learning how the libmodbus works. I am using libmodbus v3.1.7 tag from git repo. I wrote

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Filter messages by slave address

Hello. Just learning how the libmodbus works. I am using libmodbus v3.1.7 tag from git repo. I wrote

6/22/22

Minza Gayas, Chuck Watson3

6/20/22

Query Function code 43 implementation

Thanks Chuck, I need Function Code 43 and its MEI Type 14 implemented to establish Modbus RTU

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Query Function code 43 implementation

Thanks Chuck, I need Function Code 43 and its MEI Type 14 implemented to establish Modbus RTU

6/20/22

5/3/22

libmodbus rtu on rs485 seems do not transmit

Hello, i'm using libmodbus 3.1.6 on OpenWrt 21 the following simple rtu master program seems do

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libmodbus rtu on rs485 seems do not transmit

Hello, i'm using libmodbus 3.1.6 on OpenWrt 21 the following simple rtu master program seems do

5/3/22

4/22/22

"Connection timed out"

I used libmodbus for an older LinuxCNC 2.7 on preempt-rt to talk to an X200 VFD through an Adam

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"Connection timed out"

I used libmodbus for an older LinuxCNC 2.7 on preempt-rt to talk to an X200 VFD through an Adam

4/22/22

4/1/22

How to get the error response sent by my flowmeter

Hi everyone, In my flowmeter Modbus documentation, I quote : << If an error is detected in the

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How to get the error response sent by my flowmeter

Hi everyone, In my flowmeter Modbus documentation, I quote : << If an error is detected in the

4/1/22

3/28/22

Modbus Function 7 Read Exception Status

I share with you my solution based on the examples I found in the documentation, I haven't tested

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Modbus Function 7 Read Exception Status

I share with you my solution based on the examples I found in the documentation, I haven't tested

3/28/22

3/24/22

Trying to change slave id and read register

Hi, Am new to modbus implementation , im trying the set the slave id as 2, and trying to read the

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Trying to change slave id and read register

Hi, Am new to modbus implementation , im trying the set the slave id as 2, and trying to read the

3/24/22

Astrid Lindstedt

3/21/22

CRC error, rc = modbus_read_registers returns -1 .. etc ..

Dear libmodbus community, I am trying to configure a libmodbus rtu with rts: These are the printouts

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CRC error, rc = modbus_read_registers returns -1 .. etc ..

Dear libmodbus community, I am trying to configure a libmodbus rtu with rts: These are the printouts

3/21/22

3/4/22

cmake -E touch: failed to update "[...] src/libmodbus-stamp/libmodbus-download".

Hi, obviously after struggeling with the problem for days, I can solve it after posting a question

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cmake -E touch: failed to update "[...] src/libmodbus-stamp/libmodbus-download".

Hi, obviously after struggeling with the problem for days, I can solve it after posting a question

3/4/22

2/24/22

Occasional select() errors with multiple slaves on RS485 bus

Hi! I have been using libmodbus successfully for quite some time now, but I recently faced a problem

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Occasional select() errors with multiple slaves on RS485 bus

Hi! I have been using libmodbus successfully for quite some time now, but I recently faced a problem

2/24/22

Francesco Romano

1/21/22

Connection refused when trying to connect a second time to the server

Hello. I am trying to connect to a modbus TCP device twice but I get a connection refused the second

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Connection refused when trying to connect a second time to the server

Hello. I am trying to connect to a modbus TCP device twice but I get a connection refused the second

1/21/22

Δημητριος Παπαοικονόμου

12/27/21

Fwd: Problem with cross- building libmodbus

Hello, I am using conan and cmake to download and build libmodbus/3.1.6. I am getting the following

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Fwd: Problem with cross- building libmodbus

Hello, I am using conan and cmake to download and build libmodbus/3.1.6. I am getting the following

12/27/21

12/22/21

Faking a bad CRC

I am trying to edit unit-test-server.c to send a response with a bad CRC. I was thinking of using

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Faking a bad CRC

I am trying to edit unit-test-server.c to send a response with a bad CRC. I was thinking of using

12/22/21

Ramakrishna Mandalapu

12/22/21

Register initialization when different start address are provided

Hi Team, I am using modbus_mapping_t *mb_memory_section; mb_memory_section =

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Register initialization when different start address are provided

Hi Team, I am using modbus_mapping_t *mb_memory_section; mb_memory_section =

12/22/21

karl...@softart-ge.com

12/17/21

How is "Unexpected RX- Character" handled in libmodbus-RTU?

Hello, a question regarding Modbus-RTU implementation on Linux. From old times I remember bad

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How is "Unexpected RX- Character" handled in libmodbus-RTU?

Hello, a question regarding Modbus-RTU implementation on Linux. From old times I remember bad

12/17/21

Mikael Jakas, Sebastian Psm2

12/14/21

scenario: modbus_reply() works, but the rest of the server doesn't?

Hey Mikael, you mean Modbus worked perfectly, but for example the application layer has a problem?

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scenario: modbus_reply() works, but the rest of the server doesn't?

Hey Mikael, you mean Modbus worked perfectly, but for example the application layer has a problem?

12/14/21

12/2/21

Modbus socket not released after communication issue

Hello Team, I am using libmodbus library for implementing a server . Here I have an issue wherein

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Modbus socket not released after communication issue

Hello Team, I am using libmodbus library for implementing a server . Here I have an issue wherein

12/2/21

11/18/21

Windows: RTU Server (Slave): modbus_receive() blocks / hang

It only continues if I really send commands from an RTU Master (Client). ottelo schrieb am Donnerstag

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Windows: RTU Server (Slave): modbus_receive() blocks / hang

It only continues if I really send commands from an RTU Master (Client). ottelo schrieb am Donnerstag

11/18/21

11/17/21

Hooks and/or notifications for writes to mapping block

Correction: slightly updated call signature with additional context variable: modbus_mapping_t*

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Hooks and/or notifications for writes to mapping block

Correction: slightly updated call signature with additional context variable: modbus_mapping_t*

11/17/21

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