Modbus Rtu Protocol; Settings; Function Codes - Man L23/30DF Project Manual

2 Modbus RTU protocol

2.1 Settings

2.2 Function Codes

2
The Modbus RTU protocol is the standard protocol used for the communica-
tion from the GenSet.
The bus interface provides a serial connection. The protocol is implemented
according to the following definitions:
Modbus application protocol specification, Modbus over serial line speci-
fication and implementation guide,
Important
For serial Modbus communication the following hardware require-
ments must be observed:
Control Module S: Modbus RTU and Modbus ASCII possible
Gateway Module: only Modbus RTU available
There are two serial interface standards available:
RS422 – Standard, 4 + 2 wire (cable length <= 100m), cable type as
specified by the circuit diagram, line termination: 120 Ohms
RS485 – Standard, 2 + 2 wire (cable length <= 100m), cable type as
specified by the circuit diagram, line termination: 120 Ohms
The communication parameters are set as follows:
Modbus Slave
Modbus Master
Slave ID (default)
Data rate (default)
Data rate
(optionally available)
Data bits
Stop bits
Parity
Transmission mode
The following function codes are available to gather data from the SaCoS
controllers:
Function Function Code
Code (hexadecimal)
1 0x01
3 0x03
5 0x05
6 0x06
15 0x0F
16 0x10
MAN Diesel & Turbo
SaCoS
Machinery alarm system
1
57600 baud
4800 baud
9600 baud
19200 baud
38400 baud
115200 baud
8
1
None
Modbus RTU
Description
read coils
read holding registers
write coil
write single register
write multiple coils
write multiple registers
one