Programming - Siemens SIMATIC ET 200SP Equipment Manual

Programming

5.1 Programming
Data communication
Two types of data exchange between the CPU and the communications module are possible:
• Acyclic data exchange (Universal)
The point-to-point instructions communicate with the communications module
asynchronously by reading or writing data records.
Data transmission takes place across several cycles.
Note
CPU configuration limits
When using the instructions with asynchronous communication, you should take into
account the configuration limits of the respective CPU for reading and writing data
records. If multiple instructions need to read or write data records simultaneously on a
CPU, there may need to be a gap between the calls of each instruction by the user
program.
• Cyclic data exchange (Performance optimized for many short frames)
The point-to-point instructions communicate with the communications module
synchronously with the application cycle via the IO data of the communications module.
The input data comprises 32 bytes, of which 24 bytes are available for the frame. The
output data comprises 32 bytes, of which 30 bytes are available for the frame. Using cyclic
data optimizes the reaction time, especially if you are using several CM PtPs in parallel.
Note
Cyclic data exchange is available with the instruction library PtP-Communication as of
V4.0.
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CM PtP communications module (6ES7137-6AA01-0BA0)
Equipment Manual, 03/2021, A5E03790792-01
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