Implementation Of The Modbus Protocol; Bit-Type Data - Siemens SICAM Manual

B.2

Implementation of the Modbus Protocol

The device operates as a Modbus Remote Terminal Unit (RTU) slave.
Modbus Function Codes
Function Code
01
02
03
04
05
06
15
16
If the device receives an unsupported function code, it returns the exception code response as 01.
Data-Package Format
Table B-1
Baud rate (bps)
Parity
Table B-2
Modbus ID
Modbus type
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
Holding Registers
For more information about bit-type data - coil, see
SICAM, Feeder Condition Monitor, Manual
E50417-H8940-C580-A4, Edition 03.2019
Function as per Modbus Specification
Read coils
Read discrete inputs
Read holding registers
Read input registers
Write single coil
Write single register
Write multiple coils
Write multiple registers
Communication Settings
2400, 4800, 9600, 19200, 38400, 57600, 115200
O/E/N
Modbus Parameters
1 to 247
0 - Broadcast
248 to 255 Special
RTU
Inp-Reg
Hold-Reg
B.2 Implementation of the Modbus Protocol
Description
Bit access to BIT-AREA
Bit access to BIT-AREA
16-bit access to REGISTER-AREA
16-bit access to REGISTER-AREA
Bit access to BIT-AREA
16-bit access to REGISTER-AREA
Bit access to BIT-AREA
16-bit access to REGISTER-AREA
B.3 Bit-Type Data.
Modbus Registers
95