Configuring Hardware and Communication Connections STEP 7.pdf

Configuring the Distributed I/O (DP)
If especially short and secure process reaction times are desired, then free cycles
with different lengths have a definite effect on process reaction times.
With regard of the individual cycling of the input electronic module, signal or data
exchange occurs through the DP slave backplane bus, the master-slave data
exchange on the PROFIBUS subnet on to the OB 1 user program on the CPU.
The process reaction is determined in the OB 1 user program and is then sent
back over the same route to the output electronic submodule. The different lengths
and the "random" position of individual cycles have a pronounced effect on process
reaction time. Depending on the position of the individual cycles, information
transmission can either occur immediately or after two cycles.
Configuring Hardware and Communication Connections with STEP 7
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