BEI Sensors MHK5 Absolute Hollow Shaft Encoder - Manual (Page 45)

Problem
Sporadic bus errors
Possible cause
Terminating resistors not correct
Possible solution
Check terminating resistors!
The resistors of 220 Ω 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 Ω (220
Ω parallel 220 Ω).
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?
10.4 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.
AWC Abbreviation: Absoluter Winkelcodierer (German) = Absolute Rotary Encoder
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.
Configuring
When the master configures the slave the properties of the slave are specified
(e.g. number of input and output bytes).
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.
Revision 03/10 BEI Sensors Profibus Manual serie M Page 45