Technical data

➣
receives the reply frames and assigns them to the configured ZP input
bytes of the CPU
The following information is important:
➣
With field devices, different data (e.g. programming data in contrast to
signal data) can be assigned to different SAPs.
➣
ZP transmits and receives exclusively using SAP number 61.
➣
ZP uses the PROFIBUS layer 2 service SRD (send and request data)
for data transmission.
➣
The frames of the cyclic I/Os always have low priority. This means that
when there is a large volume of traffic on the bus from other stations
with higher priority, it cannot be guaranteed that ZP frames are
transmitted during a token rotation.
➣
if ZP is to transmit via the default SAP, SAP61 must be set as the
default SAP
Updating the input and output areas of the cyclic I/Os
The times at which the CP 5430 TF updates the
ZP bytes to be
transmitted
are either
➣
FREE
mode: decided by the CP (the STEP 5 control program has no
influence) or
➣
CYCLE-SYNCHRONIZED
mode: decided by the control program using
a send handling block call with job number 210.
The times at which the CP 5430 TF transfers the
received ZP bytes
to the
CPU input area are also either
➣
FREE
mode: decided by the CP (not influenced by the STEP 5 control
program) or
➣
CYCLE-SYNCHRONIZED
mode: decided by the control program by
means of a RECEIVE handling block call with job number 211.
B8976060/02 Communication with Cyclic I/Os
10 - 5 Volume 1