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https://github.com/debevv/nanoMODBUS
A compact MODBUS RTU/TCP C library for embedded/microcontrollers
https://github.com/debevv/nanoMODBUS
arduino c embedded embedded-c embedded-systems microcontroller microcontrollers modbus modbus-library modbus-rtu modbus-tcp stm32
Last synced: about 1 month ago
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A compact MODBUS RTU/TCP C library for embedded/microcontrollers
- Host: GitHub
- URL: https://github.com/debevv/nanoMODBUS
- Owner: debevv
- License: mit
- Created: 2022-01-18T02:08:39.000Z (almost 3 years ago)
- Default Branch: master
- Last Pushed: 2024-04-13T12:03:32.000Z (8 months ago)
- Last Synced: 2024-04-14T02:19:27.344Z (8 months ago)
- Topics: arduino, c, embedded, embedded-c, embedded-systems, microcontroller, microcontrollers, modbus, modbus-library, modbus-rtu, modbus-tcp, stm32
- Language: C
- Homepage:
- Size: 23 MB
- Stars: 188
- Watchers: 13
- Forks: 39
- Open Issues: 4
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
- awesome-embedded-software - nanoMODBUS - A compact MODBUS RTU/TCP C library for embedded/microcontrollers. (Protocols / Flash Memory)
README
# nanoMODBUS - A compact MODBUS RTU/TCP C library for embedded/microcontrollers
**If you found this library useful, buy me a coffee on**
[
](https://ko-fi.com/B0B2LK779)
nanoMODBUS is a small C library that implements the Modbus protocol. It is especially useful in embedded and
resource-constrained systems like microcontrollers.
Its main features are:
- Compact size
- Only ~1500 lines of code
- Client and server code can be disabled, if not needed
- No dynamic memory allocations
- Transports:
- RTU
- TCP
- Roles:
- Client
- Server
- Function codes:
- 01 (0x01) Read Coils
- 02 (0x02) Read Discrete Inputs
- 03 (0x03) Read Holding Registers
- 04 (0x04) Read Input Registers
- 05 (0x05) Write Single Coil
- 06 (0x06) Write Single Register
- 15 (0x0F) Write Multiple Coils
- 16 (0x10) Write Multiple registers
- 20 (0x14) Read File Record
- 21 (0x15) Write File Record
- 23 (0x17) Read/Write Multiple registers
- 43/14 (0x2B/0x0E) Read Device Identification
- Platform-agnostic
- Requires only C99 and its standard library
- Data transport read/write function are implemented by the user
- Broadcast requests and responses
## At a glance
```C
#include
#include "nanomodbus.h"
#include "my_platform_stuff.h"
int main(int argc, char* argv[]) {
// Set up the TCP connection
void* conn = my_connect_tcp(argv[1], argv[2]);
if (!conn) {
fprintf(stderr, "Error connecting to server\n");
return 1;
}
// my_transport_read() and my_transport_write() are implemented by the user
nmbs_platform_conf platform_conf;
nmbs_platform_conf_create(&platform_conf);
platform_conf.transport = NMBS_TRANSPORT_TCP;
platform_conf.read = my_transport_read;
platform_conf.write = my_transport_write;
platform_conf.arg = conn; // Passing our TCP connection handle to the read/write functions
// Create the modbus client
nmbs_t nmbs;
nmbs_error err = nmbs_client_create(&nmbs, &platform_conf);
if (err != NMBS_ERROR_NONE) {
fprintf(stderr, "Error creating modbus client\n");
return 1;
}
// Set only the response timeout. Byte timeout will be handled by the TCP connection
nmbs_set_read_timeout(&nmbs, 1000);
// Write 2 holding registers at address 26
uint16_t w_regs[2] = {123, 124};
err = nmbs_write_multiple_registers(&nmbs, 26, 2, w_regs);
if (err != NMBS_ERROR_NONE) {
fprintf(stderr, "Error writing register at address 26 - %s", nmbs_strerror(err));
return 1;
}
// Read 2 holding registers from address 26
uint16_t r_regs[2];
err = nmbs_read_holding_registers(&nmbs, 26, 2, r_regs);
if (err != NMBS_ERROR_NONE) {
fprintf(stderr, "Error reading 2 holding registers at address 26 - %s\n", nmbs_strerror(err));
return 1;
}
// Close the TCP connection
my_disconnect(conn);
return 0;
}
```
## Installation
Just copy `nanomodbus.c` and `nanomodbus.h` inside your application codebase.
## API reference
API reference is available in the repository's [GitHub Pages](https://debevv.github.io/nanoMODBUS/nanomodbus_8h.html).
## Platform functions
nanoMODBUS requires the implementation of 2 platform-specific functions, defined as function pointers when creating a
client/server instance.
### Transport read/write
```C
int32_t read(uint8_t* buf, uint16_t count, int32_t byte_timeout_ms, void* arg);
int32_t write(const uint8_t* buf, uint16_t count, int32_t byte_timeout_ms, void* arg);
```
These are your platform-specific functions that read/write data to/from a serial port or a TCP connection.
Both methods should block until either:
- `count` bytes of data are read/written
- the byte timeout, with `byte_timeout_ms >= 0`, expires
A value `< 0` for `byte_timeout_ms` means no timeout.
Their return value should be the number of bytes actually read/written, or `< 0` in case of error.
A return value between `0` and `count - 1` will be treated as if a timeout occurred on the transport side. All other
values will be treated as transport errors.
### Callbacks and platform functions arguments
Server callbacks and platform functions can access arbitrary user data through their `void* arg` argument. The argument
is useful, for example, to pass the connection a function should operate on.
Their initial values can be set via the `nmbs_set_callbacks_arg` and `nmbs_set_platform_arg` API methods.
## Tests and examples
Tests and examples can be built and run on Linux with CMake:
```sh
mkdir build && cd build
cmake ..
make
```
Please refer to `examples/arduino/README.md` for more info about building and running Arduino examples.
## Misc
- To reduce code size, you can define the following `#define`s:
- `NMBS_CLIENT_DISABLED` to disable all client code
- `NMBS_SERVER_DISABLED` to disable all server code
- To disable individual server callbacks, define the following:
- `NMBS_SERVER_READ_COILS_DISABLED`
- `NMBS_SERVER_READ_DISCRETE_INPUTS_DISABLED`
- `NMBS_SERVER_READ_HOLDING_REGISTERS_DISABLED`
- `NMBS_SERVER_READ_INPUT_REGISTERS_DISABLED`
- `NMBS_SERVER_WRITE_SINGLE_COIL_DISABLED`
- `NMBS_SERVER_WRITE_SINGLE_REGISTER_DISABLED`
- `NMBS_SERVER_WRITE_MULTIPLE_COILS_DISABLED`
- `NMBS_SERVER_WRITE_MULTIPLE_REGISTERS_DISABLED`
- `NMBS_SERVER_READ_FILE_RECORD_DISABLED`
- `NMBS_SERVER_WRITE_FILE_RECORD_DISABLED`
- `NMBS_SERVER_READ_WRITE_REGISTERS_DISABLED`
- `NMBS_SERVER_READ_DEVICE_IDENTIFICATION_DISABLED`
- `NMBS_STRERROR_DISABLED` to disable the code that converts `nmbs_error`s to strings
- Debug prints about received and sent messages can be enabled by defining `NMBS_DEBUG`