Recommendation For Use With A High Communications Load - Siemens SIMATIC NET CP 443-1 Advanced Manual

Configuration and operation
6.9 Interface in the user program
Note: The TSAPs can be 2-16 bytes long. The first two bytes must be occupied as
described, you can use the other bytes to suit your task.
Note
Note that the number of dynamically established connections also depends on the number of
configured, statically established connections.
You will receive corresponding condition codes on the call interface of the FBs.
Refer to the documentation of the program blocks in the online help and in the
documentation for STEP 7. There, you will also find examples of parameter assignment!
6.9.6

Recommendation for use with a high communications load

Reason
When using the CP described here, the points below will help you to avoid overload
situations on your CPU.
In particular when you replace an older CP with the CP described here and are then
confronted with overload problems, you should check your application for the pitfalls outlined
below.
Known problems
● The program blocks for sending and receiving AG_SEND / AG_RECV (FC5/FC6,
FC50/60 or FC53/63) are often called cyclically in OB1. This leads to constant
communication between the CPU and CP. As a result, other types of communication
such as PG functions cannot be executed or only very slowly.
● HMI systems access data of the CPU too often using S7 functions. This slows down
communication in general and resource bottlenecks on the CPU can occur if
SEND/RECEIVE FCs are called cyclically in OB1 (effect: reduced data throughput or
increased reaction time).
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CP 443-1 Advanced (GX30)
Manual, 03/2019, C79000-G8976-C256-05