Function Codes; Table 5-2 Supported Function Codes - Siemens SENTRON PAC RS485 Manual

The Least Significant Bit (LSB) is sent at the start of the eight data bits, and the Most
Significant Bit (MSB) is sent at the end.
See also
Configuration of the PAC RS485 expansion module on the SENTRON PAC3200 Power
Monitoring Device (Page 58)
5.1.3

Function codes

Function codes control the data exchange. In doing so, a function code tells the slave which
action it is to take.
If an error occurs, the MSB bit is set in the response frame in the FC byte.
Supported MODBUS function codes
Table 5-2
FC
02
03
04
06
10
2B
FC 02
This function code reads individual bits from the slave.
Corresponding exception codes:
Corresponding error code:
Status:
FC 03
You can read out device registers with this function code.
Number of requested registers:
Corresponding exception codes:
Corresponding error code:
PAC RS485
Manual, 02/2008, A5E02091800B-01
Supported function codes
Function in accordance with
MODBUS specification
Read Discrete Inputs
Read Holding Registers
Read Input Registers
Write Single Register
Write Multiple Registers
Read Device Identification
Parameter assignment/Addressing
Data Type
Bit Input
Register Output
Register Input
Register Output
Register
-
01, 02, 03 or 04
0x82
0 = OFF
1 = ON
At least 1 to maximum 125
01, 02, 03 or 04
0x83
5.1 MODBUS RTU
Access
R
R
R
RW
- RW
- R
31