Connection to a fieldbus
6.4 Communication via RS485
Inverter with CU240B-2 and CU240E-2 Control Units
Operating Instructions, 07/2010, FW 4.3.2, A5E02299792B AA
145
The setting using DIP switches is described in Setting the bus address via DIP switch
(Page 104).
CAUTION
A bus address that has been changed is only effective after switching-off and switching-on
again. It is particularly important that any external 24 V supply is switched off.
Additional communication settings
Table 6- 28 Parameters for setting communication via Modbus
Parameter Description
p0700 = 6 Select the command source
6: Via fieldbus
p1000 = 6 Select the setpoint source
6: Via fieldbus
p2030 = 2 Fieldbus telegram selection
2: Modbus
p2020 Fieldbus baud rate
Baud rates from 4800 bit/s to 19200 bit/s can be set for communication, factory setting =
19200 bit/s.
p2024 Modbus timing (see Section "Baud rates and mapping tables (Page 147)")
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).
p2029 Fieldbus fault statistics
Displays receive faults on the fieldbus interface
p2040 Process data monitoring time
Determines the time after which an alarm is generated if no process data are
transferred.
Note: This time must be adapted depending on the number of slaves and the baud rate
set for the bus (factory setting = 100 ms).
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