Fault-tolerant, fail-fast implementation of Modbus protocol in Go.
Purpose: this fork aims to enable modbus for concurrent usage. As such, it implements grid-x#70.
Bit access:
- Read Discrete Inputs
- Read Coils
- Write Single Coil
- Write Multiple Coils
16-bit access:
- Read Input Registers
- Read Holding Registers
- Write Single Register
- Write Multiple Registers
- Read/Write Multiple Registers
- Mask Write Register
- Read FIFO Queue
- TCP
- Serial (RTU, ASCII)
- UDP
Basic usage:
// Modbus TCP
client := modbus.TCPClient("localhost:502")
// Read input register 9
results, err := client.ReadInputRegisters(8, 1)
// Modbus RTU/ASCII
// Default configuration is 19200, 8, 1, even
client = modbus.RTUClient("/dev/ttyS0")
results, err = client.ReadCoils(2, 1)
Advanced usage:
// Modbus TCP
handler := modbus.NewTCPClientHandler("localhost:502")
handler.Timeout = 10 * time.Second
handler.SlaveID = 0xFF
handler.Logger = log.New(os.Stdout, "test: ", log.LstdFlags)
// Connect manually so that multiple requests are handled in one connection session
err := handler.Connect()
defer handler.Close()
client := modbus.NewClient(handler)
results, err := client.ReadDiscreteInputs(15, 2)
results, err = client.WriteMultipleRegisters(1, 2, []byte{0, 3, 0, 4})
results, err = client.WriteMultipleCoils(5, 10, []byte{4, 3})
// Modbus RTU/ASCII
handler := modbus.NewRTUClientHandler("/dev/ttyUSB0")
handler.BaudRate = 115200
handler.DataBits = 8
handler.Parity = "N"
handler.StopBits = 1
handler.SlaveID = 1
handler.Timeout = 5 * time.Second
err := handler.Connect()
defer handler.Close()
client := modbus.NewClient(handler)
results, err := client.ReadDiscreteInputs(15, 2)
We offer a CLI tool to read/write registers.
For simplicity, the following examples are all using Modbus TCP.
For Modbus RTU, replace the address field and use the rtu-
arguments in order to use different baudrates, databits, etc.
./modbus-cli -address=rtu:https:///dev/ttyUSB0 -rtu-baudrate=57600 -rtu-stopbits=2 -rtu-parity=N -rtu-databits=8 ...
For Modbus UDP, replace the address field with a UDP address.
./modbus-cli --address=udp:https://127.0.0.1:502 ...
Read 1 register and get raw result
./modbus-cli -address=tcp:https://127.0.0.1:502 -quantity=1 -type-parse=raw -register=42
Read 1 register and decode result as uint16
./modbus-cli -address=tcp:https://127.0.0.1:502 -quantity=1 -type-parse=uint16 -register=42
Read 1 register and get all possible decoded results
./modbus-cli -address=tcp:https://127.0.0.1:502 -quantity=1 -type-parse=all -register=42
Read 2 registers and decode result as uint32
./modbus-cli -address=tcp:https://127.0.0.1:502 -quantity=2 -type-parse=uint32 -register=42
Read 2 registers and get all possible decoded results
./modbus-cli -address=tcp:https://127.0.0.1:502 -quantity=2 -type-parse=all -register=42
Reading multiple registers is only possible in the raw format
./modbus-cli -address=tcp:https://127.0.0.1:502 -quantity=16 -type-parse=raw -register=42
Write 1 register
./modbus-cli -address=tcp:https://127.0.0.1:502 -fn-code=0x06 -type-exec=uint16 -register=42 -write-value=7
Write 2 registers
./modbus-cli -address=tcp:https://127.0.0.1:502 -fn-code=0x10 -type-exec=uint32 -register=42 -write-value=7
To release the Modbus-CLI tool, run either make release
if you have installed goreleaser
or make ci_release
.
The generated files can be found in the directory in the dist
directory.
Take the .tar.gz
and .zip
files and create a new GitHub release.