BEI Sensors PHU9 Absolute Hollow Shaft Encoder - Manual (Page 37)

PROFIBUS USER MANUAL
Preliminary 37
BEI IDEACOD SAS
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Problem
Sporadic bus errors
Possible cause
Terminating resistors not correct
Possible solution
Check terminating resistors!
The resistors of 220 must be switched on at
the beginning and at the end of the bus
segment. Switch off the power supply and
measure the resistance between the
terminals A and B in the connection cap. The resistance value must be about 110
(220 parallel 220 ).
Possible cause
EMC problems
Possible solutions
Is the used baud rate acceptable for the
length of the bus lines? Try to use lower
baud rate if necessary. Check the
connection of the cable shield in the
connection cap. Are all cables and
conductions laid according to EMC rules?
9.2 Definitions
Address
A number, which is assigned to each node, no matter whether it is a
master or slave. The address is set (non-volatile) in the connection cap
using rotary switches.
Baud rate
Data transfer rate specified as the number of bits transferred per
second (baud rate = bit rate).
Bus Node Device, which can send, receive or amplify data via the bus.
DDLM
Direct Data Link Mapper. Interface between Profibus-DP functions and
the encoder software.
DDLM_Data_Exchange Operating status of the bus, for standard data transfer.
DDLM_Set_Prm
Operating status of the bus, configuration and parameter are
transmitted
„DDLM_Slave_Diag“ Operating status, diagnostic data are requested from the slave (e.g.
encoder).
Diagnostics Identification, localization, classification, display, additional evaluation
of faults, errors and messages.
Freeze
This is a master command to the slave. This allows the master to freeze
the states of the inputs (for example of the absolute angular encoder)
to their current value. The input data are only updated again after
reception of the UNFREEZE command.