Questions tagged [modbus]

Modbus is a serial communications protocol commonly used by PLCs (programmable logic controllers) and other industrial control systems. While originally based on traditional serial communications many extensions exist to allow communication over other networks such as TCP/IP.

Filter by
Sorted by
Tagged with
0
votes
2answers
2k views

modbus_read_registers - ERROR connection timed out

We are using libmodbus library to read register values from energy meter EM6400 which supports Modbus over RTU. We are facing the following two issues. 1) We are facing issue with ...
1
vote
3answers
9k views

Serial, RS232, Modbus, UART and TCP

I want clearly know this, Serial is protocol right? Then what is the Modbus? Is it under serial. And what are RS232 and RS485? What is UART and serial and UART same? What about TCP? TCP and serial ...
3
votes
2answers
1k views

RS-485 Modbus device to MCU

I have a device (an energy meter) that sends data via RS-485 (Modbus protocol). And I want to collect it with MCU. The important thing is that I'm trying to design a board and I want it to be scalable....
0
votes
1answer
4k views

libmodbus trouble with reading from slave

I have the following code for connection to a temperature sensor as my slave using the libmodbus library in C, ...
0
votes
3answers
864 views

Arduino: RS232 Level Shifter or RS2323 Breakout needed? [closed]

I am trying to establish communications between an Arduino Mega2560 (Master) and a customised controller (Slave) via a Master-Slave RS232 link using Modbus RTU. The communication should be bi-...
0
votes
2answers
3k views

Connectors for a RS485 multipoint bus

I need to connect a bunch of Mass Flow Controllers on a RS485 (TIA-485-A) multipoint bus. I will use Modbus protocol to communicate with the devices. As specified on modbus.org (Specification and ...
0
votes
1answer
303 views

Modbus compile error Arduino

I have Code for Mod bus Library as below. I have Gone through lots of forum. How to assign device ID, slave address, length using below library function: ...
0
votes
1answer
4k views

atmega32 communicating using rs-485 modbus protocol

I am trying to read values from a meter (WDM303FDWA1) through ATmega32. The communication to the meter has to be done by RS-485 modbus protocol. I would like to know what IC do I have to use to ...
2
votes
3answers
1k views

Holding register in microcontroller for Modbus RTU

I'm very noob in microcntroller modbus. I want to do Modbus RTU slave device using RS232. I read modbus documentation from modbus.org site. But still I'm not clear about few things. How to define the ...
-1
votes
1answer
1k views

Modbus TCP/IP slave - functions

I'm developing a slave modbus TCP/IP application on the PIC32 platform. Do you have any idea about the the role of the ...
4
votes
3answers
412 views

Handling register updates in Modbus systems

I am currently developing a Modbus RTU enabled system that consists of DSP and a microprocessor that handles the Modbus communications. The DSP is sending data to the microprocessor and the ...
2
votes
3answers
34k views

Arduino as modbus master with MAX485 doesn't get any response

I'm having some troubles trying to query a modbus slave with an Arduino through RS485. I've already succeeded in querying a software modbus slave running on my PC through the USB/COM port using the ...
3
votes
2answers
517 views

What is a conventional way to set a Modbus device address and baudrate?

What's a conventional way to set an address and baud-rate/parity on a Modbus device? Is this supposed to be done using hardware switches or can be done through a software? If done through a ...
2
votes
2answers
4k views

Best way to poll for Modbus RTU slaves through a Modbus TCP gateway

I'm using a number of Modbus RTU devices connected to my PC through a Modbus TCP gateway. I'd like to poll all the available slave addresses to check which ones are available through my program. What ...
2
votes
2answers
330 views

FOSS ModBus libraries/VCl?

I'm looking for FOSS (for commercial use) VCL components for Delphi or libraries for Visual Basic/C/C++/C# ... basically, just something to abstract the h/w for development, although a h/w simulator ...
0
votes
1answer
7k views

Reading MODBUS RTU slave device Registers via RS485

i have a panel multimeter that i use for my whole house that has RS485, Modbus RTU comunication. I know what registers to read in order to get currents, voltages, power factor etc How can i use this ...