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Modbus Registers

Below is a list of available MODBUS registers. The same register numbers are also used by the MIOS-2 protocol.

Modbus Read / Write (0x17) Function

METEL IO modules have implemented the MODBUS function (0x17) Read/Write of Multiple registers. Typically it is required to have two separate requests (and responses) for:

1. Writing of outputs via MODBUS function (0x16) Writing Multiple Registers

2. Reading of inputs via MODBUS function (0x03) Read Holding Registers

This requires a total of 4 frames to be sent over MODBUS. If using 0x17 function only one request is needed for the reading and writing of outputs. This requires a total of 2 frames to be sent over MODBUS.

Default Settings of Communication

Device ID: 1
Baudrate: 115 200
Parity: None
Data bits: 8
Stop bits: 1

Subject Channel Type R/W Value Offset
States of
COIL Relay 1 DI#01 bit R 0 = inactive
1 = active
COIL Relay 2 DI#02 bit R 3002
COIL Relay 3 DI#03 bit R 3003
COIL Relay 4 DI#04 bit R 3004
COIL Relay 5 DI#05 bit R 3005
COIL Relay 6 DI#06 bit R 3006
COIL Relay 7 DI#07 bit R 3007
COIL Relay 8 DI#08 bit R 3008
Inputs DI#16 - DI#01 u16 R 0x0000 - 0x00FF 3001
Subject Channel Type R/W Value Offset
Relay Output 1 DO#01 bit RW 0 = inactive
1 = active
Relay Output 2 DO#02 bit RW 4002
Relay Output 3 DO#03 bit RW 4003
Relay Output 4 DO#04 bit RW 4004
Relay Output 5 DO#05 bit RW 4005
Relay Output 6 DO#06 bit RW 4006
Relay Output 7 DO#07 bit RW 4007
Relay Output 8 DO#08 bit RW 4008
Outputs DO#16 - DO#01 u16 RW 0x0000 - 0x00FF 4001

Note: To activate the bootloader, it is necessary to write a value 617 into the registry with an offset 1204 and restart the device.