Basic Settings For Communication - Siemens SINAMICS G120 Operating Instructions Manual

Configuring the fieldbus
8.4 Communication via RS485
8.4.3.2

Basic settings for communication

Setting the address
You can set the converter's Modbus-RTU address via the address switches on the CU via
p2021 or in STARTER under "Control Unit/Communications/fieldbus".
Valid address range: 1 ... 247
Procedure
Method
Address
switch
p2021 /
STARTER
CAUTION
For a modified bus address to be effective, you have to switch the converter and - if need
be - any external 24 V supply off and on.
Additional settings
Parameter
P0015 = 21
p2030 = 2
p2020
p2024
122
Description
If you have specified a valid address using the address switch, this address will always
be the one that takes effect and parameter p2021 cannot be changed.
The positions and settings of the address switches are described in section: Interfaces,
connectors, switches, terminal blocks and LEDs of the converter (Page 42).
Fieldbus address (factory setting: 1)
The setting in p2021 or via STARTER is effective only if you set all address switches to
"OFF" (0).
Description
Macro drive unit
Selecting the I/O configuration
Fieldbus protocol selection
2: Modbus
Fieldbus baud rate
Baud rates from 4800 bit/s to 187500 bit/s can be set for communication, factory setting
= 19200 bit/s.
Modbus timing (see Section "Baud rates and mapping tables (Page 124)")
Index 0: Maximum slave telegram processing time:

The time after which the slave must have sent a response to the master.
Index 1: Character delay time:

Character delay time: Maximum permissible delay time between the individual
characters in the Modbus frame. (Modbus standard processing time for 1.5 bytes).
Index2: Inter-telegram delay:

Maximum permissible delay time between Modbus telegrams. (Modbus standard
processing time for 3.5 bytes).
SINAMICS G120C frequency converter
Operating Instructions, 03/2012, FW V4.5, A5E02999804B AB