M-Controller II System Operation Manual - 31 -
84350-201-001 Rev C
9 MODBUS Protocol Supported By M-Controller
9.1 Serial Transmission Mode
Modbus RTU Slave Mode
Baud rate: 19.2K, 28.8K, 38.4K, and 57.6K, selectable from Modbus Baud Rate in
System Setting Menu.
Byte parity: no parity (default), Even, Odd
Data format: One start bit, 8 data bit, no parity bit, one stop bit, LSB first.
Frame Check: CRC check.
9.2 Function Code Supported by M-Controller
#03 Read Holding Registers
Function in M-Controller: Read inputs and outputs statuses and readings, such as
Relay Statuses
Analog output current (mA x 10)
Analog inputs readings
Digital Sensor readings and statuses
Buzzers, Strobe and Triggers statuses
Attribute: Read Only.
Broadcast is not supported.
Query:
Slave Address: xx (Default 03, check Slave address in M-Controller)
Function code: 03
Starting addr. Hi: 000
Starting addr. Lo: xxx (00 to 122)
No. of points Hi: 000
No. of points Lo: xxx (01 to 123)
CRC check: xxxxH
Example: to read all holding registers in M-Controller (Slave Address: 214)
Query: [214] [003] [000] [000] [000] [123] [023] [206] in unsigned decimal.
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