Questions tagged [modbus]
Modbus is a simple protocol for serial communication between electronic devices.
76 questions
0 votes
1 answer
68 views
How to faithfully collect geophone data by modbus RTU?
I am trying to collect data from a geophone using a UNO R4 minima as slave with a Zihatec shield, so that I can integrate it into a larger project on a modbus RTU bus. The signal from the geophone is ...
- 111
0 votes
1 answer
133 views
Extra 0x00 sent with RS485 message
I am currently trying to use an arduino to send an RS485 via an SP3078EEN RS485 transciever. I have my arduino code set the DE pin high, wait 1ms, then write and flush a data buffer to the serial ...
1 vote
1 answer
90 views
Interpreting Analog Output from Aalborg Mass Flow Meter GFM
I am attempting to connect this device to my computer via RS232. I am debating the simplest way of going about this and was inquiring if my Uno R3 could come into use, turning the analog symbols of 0-...
- 11
0 votes
2 answers
239 views
Using ArduinoModbus library to read a holding register with value -1
client.read() function in ArduinoModbus library returns -1 on failure: https://www.arduino.cc/reference/en/libraries/arduinomodbus/client.read/. How can it be used to read a holding register with ...
- 209
3 votes
0 answers
108 views
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. ...
- 31
0 votes
1 answer
75 views
How to make MQTT and ArduinoModbus libraries working on the same Ethernet port?
I have a SAMD51P20 based Arduino PLC with WIZnet W5500 based Ethernet shield. I'm using these libraries: #include <Ethernet.h> #include <MQTT.h> #include <ArduinoModbus.h> MQTT and ...
- 209
0 votes
2 answers
412 views
ArduinoModbus / RS485 conflict between Serial and Serial1
I am attempting implement ArduinoModbus on my STM32 Poternta H7 using the breakout board. Its well documented that in ArduinoRS485 that the RS485 object is hardwired. If you are using the PH7/Breakout ...
- 33
1 vote
1 answer
274 views
Modbus rtu server library which logs the requests
Kindly seek help. In my project I want to ‘fake’ a smart meter via Modbus rtu server for a solis inverter. Somehow the solis realizes that I am faking him, so I am wondering which Modbus rtu server ...
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0 votes
0 answers
187 views
Arduino RS485 do I need MAX485?
I'm trying to connect sesnor that use RS485 (I'm almost sure that's modbus). The sensor has RX/TX and +/- wires. Do I still need a component between the RX/TX pin from the Arduino UNO and the sensor ...
- 9
2 votes
0 answers
380 views
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 ...
- 151
1 vote
0 answers
214 views
Trying to use an Arduino Uno to control two slaves with one master but its not working
I am trying to use following code but its not working. Need a help in this regard. #include <SimpleModbusMaster.h> #define baudrate 115200 #define timeout 2000 #define polling 500 #define ...
- 11
2 votes
0 answers
791 views
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, ...
- 159
-1 votes
1 answer
971 views
Cannot read values stored in bool* pointer [closed]
I'm trying to read values stored in a bool* pointer from a modbus coil call. I'm using modbus-esp8266 library. it's all ok with Input Registers and Holding Registers but i cannot read the result of a ...
- 101
0 votes
0 answers
1k views
ESP8266 - MAX3485 Modbus not getting data
I'm trying to connect a modbus meter to a nodeMcu LoLin v3 I'm using a MAX3485 module to transfer the TTL to a RS485 connection. The modbus server has unitId 1, baud rate 9600 and no Parity This is ...
- 101
2 votes
1 answer
4k views
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 ...
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