Table of Contents
15 modbus.get parameters
Overview
The table below presents details of the modbus.get[] item parameters.
Parameters
| Parameter | Description | Defaults | Example |
|---|---|---|---|
| endpoint | Protocol and address of the endpoint, defined as protocol://connection_stringPossible protocol values: rtu, ascii (Agent 2 only), tcp Connection string format: with tcp - address:portwith serial line: rtu, ascii - port_name:speed:paramswhere 'speed' - 1200, 9600 etc 'params' - data bits (5,6,7 or 8), parity (n,e or o for none/even/odd), stop bits (1 or 2) |
protocol: none rtu/ascii protocol: port_name: none speed: 115200 params: 8n1 tcp protocol: address: none port: 502 |
tcp://192.168.6.1:511 tcp://192.168.6.2 tcp://[::1]:511 tcp://::1 tcp://localhost:511 tcp://localhost rtu://COM1:9600:8n ascii://COM2:1200:7o2 rtu://ttyS0:9600 ascii://ttyS1 |
| slave id | Modbus address of the device it is intended for (1 to 247), see MODBUS Messaging Implementation Guide (page 23) tcp device (not GW) will ignore the field |
serial: 1 tcp: 255 (0xFF) |
2 |
| function | Empty or value of a supported function: 1 - Read Coil, 2 - Read Discrete Input, 3 - Read Holding Registers, 4 - Read Input Registers |
empty | 3 |
| address | Address of the first registry, coil or input. If 'function' is empty, then 'address' should be in range for: Coil - 00001 - 09999 Discrete input - 10001 - 19999 Input register - 30001 - 39999 Holding register - 40001 - 49999 If 'function' is not empty, the 'address' field will be from 0 till 65535 and used without modification (PDU) |
empty function: 00001 non-empty function: 0 |
9999 |
| count | Count of sequenced 'type' which will be read from device, where: for Coil or Discrete input the 'type' = 1 bit for other cases: (count*type)/2 = real count of registers for reading If 'offset' is not 0, the value will be added to 'real count' Acceptable range for 'real count' is 1:65535 |
1 | 2 |
| type | Data type: for Read Coil and Read Discrete Input - bit for Read Holding Registers and Read Input Registers: int8 - 8bit uint8 - 8bit (unsigned) int16 - 16bit uint16 - 16bit (unsigned) int32 - 32bit uint32 - 32bit (unsigned) float - 32bit uint64 - 64bit (unsigned) double - 64bit |
bit uint16 |
uint64 |
| endianness | Endianness type: be - Big Endian le - Little Endian mbe - Mid-Big Endian mle - Mid-Little Endian Limitations: for 1 bit - be for 8 bits - be,le for 16 bits - be,le |
be | le |
| offset | Number of registers, starting from 'address', the result of which will be discarded. The size of each register is 16bit (needed to support equipment that does not support random read access). |
0 | 4 |