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Questions tagged [modbus]

Modbus is a simple protocol for serial communication between electronic devices.

76 questions
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How to interconnect multiple Arduinos with a Rpi to control home-lights/switches

While planning the lightning infrastructure (wall-switches and lights) of my new home (it's still under-construction) I choosed to go through the "automated route" way and due to my background (I'm an "old" system/network administrator with…
Damiano Verzulli
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When it comes to UART to RS485 communication, what is the difference between the 'MAX485' and the 'HW-0519' module?

I recently found this model with the ID 'HW-0519' on it. It can be found online (HW-0519 in Aliexpress) and is sold for the purpose of converting UART to RS485 communication using Arduino devices. The MAX485 module (MAX485 in Banggood) is the more…
C Vith
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Modbus TCP/IP using Arduino uno and ENC28J60 module

I have this project where I need a modbus tcp server that will host a series of sensor data for other modbus client devices to read. I use this Library by Andresoarmento This is the code i am using from the library example: #include…
Deadpool
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Modbus Communication protocol for Arduino as Slave

I have an Arduino Uno board, with these components: rs-485 Modbus module shield Multiprotocol radio shield board for Arduino In addition I have a level sensor which reads either 1 when it is above water, and 0 when it is below. I need to be able…
lshas
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Modbus RTU controller monitoring with arduino and RS485 module

I'm a medium user in Arduino. I baught a pHmeter controller with RS485 output (MODBUS RTU protocol). I want to get pH value read by the controller over RS485 module and Arduino. According the controller's manufacturer, we should operate as…
Teddol
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Why RTU bridge timeout even though answer is received?

I'm testing the following code as a bridge between https://sourceforge.net/projects/qmodmaster/ and https://pypi.org/project/pyModSlave/. As hardware, I'm using a NodeMCU 1.0 and a USB/TTL converter. The Modbus library is…
Eduardo-bat
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Is there any good working MODBUS TCP master library available for Arduino?

I would like to connect with Fronius solar inverter through MODBUS TCP with Arduino to READ and WRITE register values only. I want to set the Arduino as master and the Inverter as slave. I want to use only two functions "Read Holding Registers" and…
Prayuktibid
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Arduino throwing error while using modbus RS485 code

I have been trying to make a communication with my industrial drive. All I want to do is read a few values of drive, like current, voltage etc. For that I am using a library: I don't understand why it's happening. When the same code I have used…
user16682
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Negative value conversion for modbus slave

I have an analog sensor which reads values 0-5v, -75 degrees to 75 degrees. Now I have converted to +75 degrees and -75 degrees format depend on the voltage. From 2.5v to 5v data is read properly (i.e 0-75 degree), but from 0-2.5v they are negative…
AMPS
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Response of Modbus Protocol

I have the below code. This code is successfully compiling and uploading, but I am not getting any response from Slave. What do I need to do? Some time data being received from Slave (I get this error): My main code: #define ID 1 /*static float…
AMPS
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Modbus RS485 Decode the message received

I'm try to read some value from a soil NPK sensor using RS485 Modbus e Arduino uno. I menage to sent the request msg and I got the response but now i don't know how to read the response in order to get the information I need. the following code sent…
Damiano Miazzi
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Using ModbusRTU.h, what would cause holding registers all read 0?

I'm working with a 32-Input Modbus RTU module using RS485. I'm trying to read/poll the inputs to check for ON(1) states. I have tested this module with Arduino UNO, Radzio! Modbus Master simulator, and Modbus Poll -- all worked as expected,…
Ashton
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ModbusMaster.h - changing node

I'm using the ModbusMaster.h library on a project, with arduino-uno and a TTL/RS-485 converter, and the function has to identify the slave that it is communicating. The slaves goes from 1 to 16. After I've begun the connection, ModbusMaster…
Claudiaum
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Modbus rtu data decimal to float conversion

Hi,am trying to communicate with power-factor controller [Selec APFC 148-312] using modbus RTU,am following example sketch from modbusmaster library. am able to get the raw data from the instrument but data structure seems to be in decimal…
Ragaven N
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Which sensor bus best to use?

I am working on a project which requires a dozen VL53l0X I2C-TOF sensors to be polled by one master MCU over a few meters of cable. Thus, I decided to accompany each TOF by an Atmega8 acting as a gateway between the TOF and a Modbus (using a…
Daniel D.
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