https://github.com/yaacov/arduinomodbusslavetcp
Modbus slave library for ESP8266-Arduino
https://github.com/yaacov/arduinomodbusslavetcp
Last synced: 6 months ago
JSON representation
Modbus slave library for ESP8266-Arduino
- Host: GitHub
- URL: https://github.com/yaacov/arduinomodbusslavetcp
- Owner: yaacov
- License: isc
- Created: 2015-12-16T12:00:55.000Z (almost 10 years ago)
- Default Branch: master
- Last Pushed: 2018-07-15T12:42:40.000Z (about 7 years ago)
- Last Synced: 2025-03-24T19:52:46.105Z (7 months ago)
- Language: C++
- Size: 10.7 KB
- Stars: 19
- Watchers: 5
- Forks: 10
- Open Issues: 2
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# ModbusSlaveTCP
##### ModbusSlave library for ESP8266-Arduino
This modbus slave library uses callbacks to handle modbus requests.
Handler functions are called on modbus request, and the users can implement them in their sketch.
### ModbusSlave is fun and easy to use
Register a handler function:
```c
slave.cbVector[CB_READ_REGISTERS] = ReadAnalogIn;
```
Implement it:
```c
void ReadAnalogIn(uint8_t fc, uint16_t address, uint16_t length) {
for (int i = 0; i < length; i++)
slave.writeRegisterToBuffer(i, analogRead(address + i));
}
```
And thats it, your sketch is modbus enabled. (see the full examples for more detail)
----
- [Install](#install)
- [Competabilty](#competabilty)
- [Callback vector](#callback-vector)
- [Slots](#slots)
- [Handler function](#handler-function)
- [Function codes](#function-codes)
- [Reading and writing to the request buffer](#reading-and-writing-to-the-request-buffer)
- [Examples](#examples)
- [handle "Force Single Coil" as arduino digitalWrite](#handle-force-single-coil-as-arduino-digitalwrite)
- [handle "Read Input Registers" as arduino analogRead](#handle-read-input-registers-as-arduino-analogread)
----
### Install
Download the zip package, and install it into your Arduino IDE.
See the Arduino tutorial about installing 3rd party libraries: https://www.arduino.cc/en/Guide/Libraries#toc4
### Competabilty
###### This class implements:
* FC1 "Read Coil Status"
* FC2 "Read Input Status"
* FC3 "Read Holding Registers"
* FC4 "Read Input Registers"
* FC5 "Force Single Coil"
* FC16 "Preset Multiple Registers"
### Callback vector
Users register handler functions into the callback vector.
###### Slots
The callback vector has 4 slots for request handlers:
* slave.cbVector[CB_READ_COILS] - called on FC1 and FC2
* slave.cbVector[CB_WRITE_COIL] - called on FC5
* slave.cbVector[CB_READ_REGISTERS] - called on FC3 and FC4
* slave.cbVector[CB_WRITE_MULTIPLE_REGISTERS] - called on FC16
###### Handler function
handler functions must return void and take:
* uint8_t fc - request function code
* uint16_t address - first register / first coil address
* uint16_t length / status - length of data / coil status
###### Function codes
* FC_READ_COILS = 1
* FC_READ_DISCRETE_INPUT = 2
* FC_READ_REGISTERS = 3
* FC_READ_INPUT_REGISTERS = 4
* FC_WRITE_COIL = 5
* FC_WRITE_MULTIPLE_REGISTERS = 16
----
###### Reading and writing to the request / response buffer
* uint16_t readRegisterFromBuffer(int offset) : read one register value from the request buffer.
* void writeCoilToBuffer(int offset, uint16_t state) : write one coil state into the answer buffer.
* void writeRegisterToBuffer(int offset, uint16_t value) : write one register value into the answer buffer.
----
### Examples
----
###### handle "Force Single Coil" as arduino digitalWrite
```c
#include
#include
const char* ssid = "....";
const char* pass = "....";
Modbus slave(1); // slave id = 1
void setup() {
// connect to WiFi
WiFi.begin(ssid, pass);
while (WiFi.status() != WL_CONNECTED) delay(500);
// register one handler functions
// if a callback handler is not assigned to a modbus command
// the default handler is called.
// default handlers return a valid but empty replay.
slave.cbVector[CB_WRITE_COIL] = writeDigitlOut;
// start slave at port 502
slave.begin(); // start listen on port 502
}
void loop() {
// listen for modbus commands con serial port
slave.poll();
}
// Handel Force Single Coil (FC=05)
void writeDigitlOut(uint8_t fc, uint16_t address, uint16_t status) {
if (status == HIGH) {
digitalWrite(address, HIGH);
} else {
digitalWrite(address, LOW);
}
}
```
----
###### handle "Read Input Registers" as arduino analogRead
```c
#include
#include
const char* ssid = "....";
const char* pass = "....";
Modbus slave(1); // slave id = 1
void setup() {
// connect to WiFi
WiFi.begin(ssid, pass);
while (WiFi.status() != WL_CONNECTED) delay(500);
// register handler functions
slave.cbVector[CB_READ_REGISTERS] = ReadAnalogIn;
// start slave at port 502
slave.begin(); // start listen on port 502
}
void loop() {
// listen for modbus commands con serial port
slave.poll();
}
// Handel Read Input Registers (FC=04)
void ReadAnalogIn(uint8_t fc, uint16_t address, uint16_t length) {
// we only answer to function code 4
if (fc != FC_READ_INPUT_REGISTERS) return;
// write registers into the answer buffer
for (int i = 0; i < length; i++) {
slave.writeRegisterToBuffer(i, analogRead(address + i));
}
}
```