Technical data

Communication
9.3 Communication via PROFIBUS DP
Function Manual
638 Function Manual, 06/2012, 6SL3097-4AB10-0BP4
User data integrity
User data integrity is verified in both transfer directions (master ↔ slave) by a sign of life (4-
bit counter).
The sign of life counters are incremented from 1 to 15 and then start again at 1.
● Master sign of life
– STW2.12 ... STW2.15 are used for the master sign of life.
– The master sign of life counter is incremented in each master application cycle
(TMAPC).
– The number of sign-of-life errors tolerated can be set via p0925.
– p0925 = 65535 deactivates sign-of-life monitoring on the slave.
– Monitoring
The master sign of life is monitored on the slave and any sign-of-life errors are
evaluated accordingly.
The maximum number of tolerated master sign-of-life errors with no history can be set
via p0925.
If the number of tolerated sign-of-life errors set in p0925 is exceeded, the response is
as follows:
– A corresponding message is output.
– The value zero is output as the slave sign of life.
– Synchronization with the master sign of life is started.
● Slave sign of life
– ZSW2.12 ... ZSW2.15 are used for the slave sign of life.
– The slave sign of life counter is incremented in each DP cycle (T
DP
).
9.3.4 Slave-to-slave communication
9.3.4.1 General information
For PROFIBUS DP, the master addresses all of the slaves one after the other in a DP cycle.
In this case, the master transfers its output data (setpoints) to the particular slave and
receives as response the input data (actual values). Fast, distributed data transfer between
drives (slaves) is possible using the "slave-to-slave communication" function without direct
involvement from the master.