6-20
Communications Processor CP 541
EWA 4NEB 812 6188-02
6.4
DP Diagnosis in the Programmable Controller
The CP 541 informs the connected programmable controller of a failure of
the DP connection to the DP master.
This chapter describes how this is achieved and what you must take into ac-
count.
The connection to the DP master is monitored as soon as the CP 541 is ac-
cepted in the DP cycle as a DP slave, and the DP watchdog in CP 541 has
been activated.
If the CP 541 detects a failure of the DP master or of the connection to the
DP master, it reacts as follows:
The CP 541 sends a “zero” message to the programmable controller.
The CP 541 sets bit 1 in the CBR (see below).
In the “zero” message, all data contain the value 0 (closed-circuit principle).
The message has the length you specified with parameter NWI in frame DPS.
When the CP 541 is used with the DP connection, the receive coordination
byte (CBR) must be interpreted as follows:
Bit 1 is always reset by the CP 541 in normal operation.
The CP 541 sets bit 1 in the CBR in the event of failure of the DP master.
Take the following actions:
Inspect the connection of the DP master to SINEC L2.
Check SINEC L2.
Verify proper functioning of the DP master.
Check the watchdog specified in the DP master for the connection be-
tween DP master and CP 541.
Introduction
DP Master
Monitoring
Reaction of the
CP 541
Zero Message
CBR
Remedy
Diagnostics and Error Handling
