6.6
Drive control via Modbus RTU
Modbus RTU is used to transfer cyclic process data and acyclic parameter data between
precisely one master and up to 247 slaves. The inverter is always the slave, and sends data
when requested to do so by the master. Slave-to-slave communication is not possible.
Settings for Modbus RTU
Parameter
Explanation
p2020
Fieldbus interface baudrate
(Factory setting: 7)
5: 4800 baud
6: 9600 baud
7: 19200 baud
8: 38400 baud
9: 57600 baud
10: 76800 baud
11: 93750 baud
12: 115200 baud
13: 187500 baud
p2021
Fieldbus interface address (Factory setting: 1)
Valid addresses: 1 … 247.
The parameter is only active if address 0 is set at the Control Unit address switch.
A change only becomes effective after the inverter power supply has been switched off
and switched on again.
p2024
Fieldbus interface times (Fac‐
tory setting: [0] 1000 ms,
[2] 0 ms)
[0] Maximum permissible telegram processing time of
the Modbus slave
[2] dead time between two telegrams
r2029
Fieldbus interface error statis‐
tics
[0] number of error-free
telegrams
[1] number of rejected tele‐
grams
[2] number of framing er‐
rors
[3] number of overrun er‐
rors
[4] number of parity errors
[5] number of starting char‐
acter errors
[6] number of checksum
errors
[7] number of length errors
p2030 = 2
Fieldbus interface protocol selection: Modbus RTU
p2031
Fieldbus interface Modbus
parity (Factory setting: 2)
0: No parity
1: Odd parity
2: Even parity
p2040
Fieldbus interface monitoring time (Factory setting: 100 ms)
p2040 = 0: The monitoring is deactivated
Control word 1 (STW1)
Bit Meaning
Explanation
Signal inter‐
connection in
the inverter
0
0 = OFF1
The motor brakes with the ramp-down time p1121 of
the ramp-function generator. The inverter switches off
the motor at standstill.
p0840[0] =
r2090.0
0 → 1 = ON
The inverter goes into the "ready" state. If, in addition
bit 3 = 1, then the inverter switches on the motor.
Advanced commissioning
6.6 Drive control via Modbus RTU
SINAMICS G120C converter
194
Operating Instructions, 09/2017, FW V4.7 SP9, A5E34263257B AF