Siemens SICAM, Manual, Page: 95 / 174

Implementation of the Modbus Protocol
The device operates as a Modbus Remote Terminal Unit (RTU) slave.
Modbus Function Codes
Function Code Function as per Modbus Specification Description
01 Read coils Bit access to BIT-AREA
02 Read discrete inputs Bit access to BIT-AREA
03 Read holding registers 16-bit access to REGISTER-AREA
04 Read input registers 16-bit access to REGISTER-AREA
05 Write single coil Bit access to BIT-AREA
06 Write single register 16-bit access to REGISTER-AREA
15 Write multiple coils Bit access to BIT-AREA
16 Write multiple registers 16-bit access to REGISTER-AREA
If the device receives an unsupported function code, it returns the exception code response as 01.
Data-Package Format
Table B-1 Communication Settings
Baud rate (bps) 2400, 4800, 9600, 19200, 38400, 57600, 115200
Parity O/E/N
Table B-2 Modbus Parameters
Modbus ID 1 to 247
0 - Broadcast
248 to 255 Special
Modbus type RTU
In the SICAM FCM, the data-byte standard setting is as follows:
•
1 start bit
•
8 data bits (LSB first)
•
1 parity bit (odd/even/none)
•
1 stop bit
Modbus Data
The device supports the following data types:
•
Bit-type data (discrete inputs/coil)
•
Register-type data
The following abbreviations are used for the register names:
Input Registers Inp-Reg
Holding Registers Hold-Reg
For more information about bit-type data - coil, see B.3 Bit-Type Data .
B.2
Modbus Registers
B.2 Implementation of the Modbus Protocol
SICAM, Feeder Condition Monitor, Manual 95
E50417-H8940-C580-A4, Edition 03.2019