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.
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Connecting L&T Qusar Meter to Laptop using CAS MODBUS SCANNER
I am trying to connect Quasar meter with my laptop. Quasar meter has MODBUS RTU protocol with RS485 communication channel. I am converting RS485 to RS232 and then through serial adapter I am ...
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1answer
42 views
Difficulty in reading values Modbus application in Python(Pyserial) On Energy meter (EM6400)
I am trying to read energy meter(EM6400) voltage values in python by using modbus protocol.
But there are issues when I am reading values. I think the issue is ...
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1answer
49 views
To connect arduino uno with energy meter
How do I interface between Energy Meter having MODBUS RTU protocol with RS485 communication to Arduino Uno?
I am using MAX 485 to convert RS485 to TTL. And I have done coding in ModbusMaster library. ...
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0answers
8 views
Invertek Optidrive E2 Modbus
Has anyone communicated to an Invertek Optidrive E2 using Modbus? Even when I follow the way the user guide indicates it should be done, I get responses consisting of a whole lot of zeroes. E.G.
I ...
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1answer
58 views
Modbus and the Sunny Boy
I am using libmodbus to connect to the a SunnyBoy 2.5 inverter. I make the connection as follows:
...
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2answers
75 views
Microcontroller Interface with Modbus Serial [closed]
I'm a beginner and I'm trying to acquire data from a microcontroller with Modbus serial protocol in order to create an interface with LabVIEW. I'm using a Prolific Technology USB-RS232 converter and ...
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1answer
80 views
Theoretical fastest polling speed for RS-485
I have a system of 36 sensor assemblies that I'd like to quickly poll the state of several times per second. Each one of these assemblies includes a Teensy 3.1 board connected to an analog sensor and ...
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2answers
58 views
Put firewall hardware with ethernet ports between serial ports
I want to put a firewall hardware product between a RTU and PLC to block some Modbus function codes (e.g. write coil, read coil). (This firewall product is able to do deep packet inspection on Modbus ...
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1answer
72 views
Modbus raw data COM capture file example?
I'm attempting to use a RS232 tap to sniff a serial connection between two devices that are communicating using Modbus RTU.
I'm looking for any capture files taken from sniffing a COM connection or ...
4
votes
1answer
116 views
RS485 not working in pic24fj128ga202
I would like to send and receive data between two PIC24F microcontrollers via RS485. Here i'm using SP3485 IC. I've set one microcontroller as
transmitter and another one has receiver. My ...
4
votes
3answers
151 views
RxTx communication with multiple slaves using a RaspberryPi
I am a programmer trying to build a circuit with limited EE knowledge. With so many options(at least being new to this), just want to make sure I am going down the right path.
What I am trying to ...
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1answer
83 views
Modbus RS485 - Voltage greater than 12V?
I have a boiler (Immergas Eolo Star) which has 2 pins where you can connect either a normal thermostat or a "remote control unit" which can also give more detailed information (self-diagnosis) about ...
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3answers
357 views
Struggling with serial communication over RS 485 using modbus protocol
I have around 60-70 inverters that I want to talk to using arduino over RS-485. The connection that I am making with arduino is according to the attached image.
Now I think that my connection part ...
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1answer
115 views
Modbus Rs-485 serial communication and polling with reference to manual
I have connected my slave and RS-485 using serial connection and using my computer as master device.
I'm able to poll but I cant figure out which registers I'm polling as shown in image 1.
I tried to ...
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2answers
184 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 ...
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3answers
435 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 ...
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2answers
304 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 ...
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0answers
192 views
Modbus over USB-CDC and similar
Modbus RTU (Specification) is a protocol that's designed to be used with transports with relatively precise timing, which native serial ports can handle. It uses the timing to handle framing the ...
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1answer
2k 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,
...
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2answers
230 views
Arduino: RS232 Level Shifter or RS2323 Breakout needed?
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 ...
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2answers
829 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 ...
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1answer
215 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:
...
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1answer
2k 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 ...
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3answers
751 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 ...
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1answer
570 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 ...
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2answers
184 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
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2answers
19k 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
202 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
2k 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 ...
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2answers
241 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 ...
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1answer
6k 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 ...
