andresarmento / modbus-esp8266

A library that allows your ESP8266 to communicate via Modbus protocol, acting as a slave (master in development). Supports IP via wireless network (Modbus IP).

Modbus Library for ESP8266

This library allows your ESP8266 to communicate via Modbus protocol. The Modbus is a master-slave protocol used in industrial automation and can be used in other areas, such as home automation.

The Modbus generally uses serial RS-232 or RS-485 as physical layer (then called Modbus Serial) and TCP/IP via Ethernet or WiFi (Modbus IP).

In the current version the library allows the ESP8266 operate as a slave, supporting Modbus IP via wireless network. For more information about Modbus see:

http://pt.wikipedia.org/wiki/Modbus http://www.modbus.org/docs/Modbus_Application_Protocol_V1_1b.pdf http://www.modbus.org/docs/Modbus_Messaging_Implementation_Guide_V1_0b.pdf

Features

• Operates as a slave
• Supports Modbus IP (TCP, not keep-alive)
• Reply exception messages for all supported functions
• Modbus functions supported:
• 0x01 - Read Coils
• 0x02 - Read Input Status (Read Discrete Inputs)
• 0x03 - Read Holding Registers
• 0x04 - Read Input Registers
• 0x05 - Write Single Coil
• 0x06 - Write Single Register
• 0x0F - Write Multiple Coils
• 0x10 - Write Multiple Registers

Notes:

1. When using Modbus IP the transport protocol is TCP (port 502) and the connection is terminated to each transmitted message, that is, is not a keep-alive type connection.

2. The offsets for registers are 0-based. So be careful when setting your supervisory system or your testing software. For example, in ScadaBR (http://www.scadabr.com.br) offsets are 0-based, then, a register configured as 100 in the library is set to 100 in ScadaBR. On the other hand, in the CAS Modbus Scanner (http://www.chipkin.com/products/software/modbus-software/cas-modbus-scanner/) offsets are 1-based, so a register configured as 100 in library should be 101 in this software.

3. Early in the library Modbus.h file there is an option to limit the operation to the functions of Holding Registers, saving space in the program memory. Just comment out the following line:

#define USE_HOLDING_REGISTERS_ONLY

Thus, only the following functions are supported:

• 0x03 - Read Holding Registers
• 0x06 - Write Single Register
• 0x10 - Write Multiple Registers

How to

This README is under development, for now, see the examples of the library.

Contributions

http://github.com/andresarmento/modbus-esp8266
prof (at) andresarmento (dot) com

License

The code in this repo is licensed under the BSD New License. See LICENSE.txt for more info.

modbus-esp8266's Issues

can't use slave ID with TCP Client?

Hi there, thanks for this library. I have got the example going on my ESP32 for modbus TCP client and I can read and write registers from my PC using modbus TCP query program from SimplyModbus. However, the client (ESP32) behaves the same no matter what I set the modbus slave ID to - it doesn't seem to pay any attention to that number.

In this application I'm working on I need to be able to respond differently depending on which slave ID the query is sent to. Is there a way to check ID for an incoming request?

Thanks for any thoughts.

WeMos D1 (ESP8266 board) to be used as Arduino to talk MODBUS to SCADA

I would like to use WeMos D1 R2 board (ESP8266 based) as Arduino controller to communicate with SCADA system over MODBUS IP protocol. I am using Home Edition of mySCADA software from http://www.myscada.org/

I am a bit confused with different flavors of libraries and multiple possible software/hardware configurations. I would appreciate detailed instructions how to set it up. Thank you,

Reset many times

i program the esp8266 esp-07 but it resets many times and randomly! the node mcu board works about 117 hours but the esp-07 works about 23 hours and then it resets what is the problem?????

adding regs

can you help,look at my project file and me what's wrong, please

ESP12E_modified.zip

Works well but need to be disconnected and reconnected

Hi
Thanks for your library. I tested with NODEMCU DEVKIT 1 and arduino 1.6.5. CAS Modbus scanner on PC. I tried the holding register example. I find that the after each poll by CAS I have to disconnect and reconnect else CAS shows no response from device after the 1st read.

Does the library support ESP32-Wroom

I want to use the wifi capabilities of the ESP32 Does the library support ESP32?

TCP server port

Hello. I having a problem where I want to read holding registers from modbus tcp (as modbus master) but it failed. This is because the example code didn't provide server port. I want to use this address 192.168.0.1:8899 to read but it failed because the code defined as 192.168.0.1. I used IP-Client-SimpleRead.ino

Modbus serial on ESP8266

Hi,
Thanks a lot for this lib. I'm trying to use modbus serial on a ESP8266 but I'm not sure what to do, do I need to take ModbusSerial lib from modbus-arduino (there is none on esp8266 lib) and Modbus library from modbus-esp8266, is that correct ?

Issues with Input address 7 reading correct value.

Having issues with reading the correct value on mb.Ists(7, 1);. Reading a zero and not a 1.

/****************************************************/
// Address 1 on the PLC is Address 0 on the ESP8266
for (index1 = 0; index1 < 32; index1++)
{
mb.addIsts(index1);
}

void loop() {
//Call once inside loop() - all magic here
mb.task();
if (millis() > timer0 + 2000) {
timer0 = millis();
mb.Ists(0, 1);

   mb.Ists(3, 1);

   mb.Ists(5, 1);

   mb.Ists(6, 1);

   mb.Ists(7, 1);

   mb.Ists(8, 1);


  }  

Timestamp problem

if (millis() > ts + 2000)
?

if (millis() - ts > 2000)
!

Tcp Keep Alive - modbus-esp8266

Hi all!

Is there a way to keep tcp alive in modbus-esp8266 like "https://github.com/andresarmento/modbus-arduino" ?

I commented "client.stop();" in the file "ModbusIP_ESP8266.cpp" but there was no result.

Thanks.

Regarding ESP8266WiFi.h

Greetings,

On Arduino version 1.6.9, I manage to install ModbusIP library and compile provided examples.

I would like to implement modbus_esp8266.
Unfortunately I have faced some issues.
When I try installing modbus-esp8266 via >Sketch>Include Library>add. ZIP library, Arduino ide complains with the followings:

Arduino: 1.6.9 (Windows 7), Board: "NodeMCU 1.0 (ESP-12E Module), 80 MHz, 115200, 4M (3M SPIFFS)"
Specified folder/zip file does not contain a valid library

What can be possible reason of this error message?

Regards,

Support for ESP8266 Modbus Master

If this library supports Modbus Master for ESP8266.?