Siemens SENTRON PAC4220 - Appendix; A.1 Modbus; A.1.1 Modbus; A.1.2 Function Codes

Appendix
A
A.1 Modbus
A
.1.1
Modbus
Detailed information about Modbus can be found at the Modbus website (
https://modbus.org/).
You can acces
s the following measured variables:
• Via the Ethernet interface with the ModbusTCP protocol
• Via the PACRS485 expansion module with the ModbusRTU protocol
More information
You can 󹪝nd further details about the PACRS485 expansion module and ModusRTU in the
"PACRS485 Expansion Module" equipment manual.
A.1.2 Function codes
Function codes control the data exchange. To do this, a function code tells the device what
action it is to take.
If an error occurs, the most signi󹪝cant bit (MSB) is set in the FCbyte of the response frame.
Supported Modbus function codes
FC Function in accordance with Modbus speci󹪝cation
0x01 Read Coils
0x02 Read Discrete Inputs
0x03 Read Holding Registers
0x04 Read Input Registers
0x05 Write Single Coil
0x06 Write Single Register
0x0F Write Multiple Coils
0x10 Write Multiple Registers
0x2B Read Device Identi󹪝cation
0x14 Read File Record (for average demand values)
PAC4220
Equipment Manual, L1V30827278B-01 113