REXROTH Fv Series, Instruction Manual

Page: 182 / 222

Similarly, if the interval between a new frame and the previous one is less
than 3.5 characters, the receiving device will consider it as a part of the previ‐
ous frame. Due to confusion of the frames, the CRC check will fail and lead
to a communication fault.
Data format and sending sequence of one byte:
●
1 start bit, 8 data bits
● 1 parity check bit or no parity check bit
● 1 or 2 stop bits
CRC (Cyclic redundancy check):
●
CRC16, lower bytes first and higher bytes later
Slave address:
●
The address of a frequency converter may be any between 1 and 247.
● The address 0 is reserved for broadcasting. Frequency converters will
act upon its request but make no acknowledgement.
● Each address must be unique in the network.
12.2.2 Interface
The communication interface of Fv converters is shown in fig. 12-2 "Fv com‐
munication interface" on page 180 :
Fig.12-2: Fv communication interface
12.2.3 Protocol Functions
Supported Functions
The main function of ModBus is to read and to write parameters. Different
function codes decide different operation requests. ModBus functions man‐
aged by Fv converters and their limits are shown in fig. 12-3 "ModBus func‐
tions managed by Fv converters and their limits" on page 180 .
Function
code
Description Broadcast Maximum value of
N
3=0x03 Read N register parameters NO
16 characters
in maximum
6=0x06
Rewrite a register with information
stored even after power off
YES －
8=0x08 Loop test NO －
Bosch Rexroth AG DOK-RCON02-FV*********IB01-EN-P
Rexroth Frequency Converter Fv
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Communication Protocols