Communication in SIMATIC S7-300/400/1200/1500
11
11.1 General information
A SIWAREX WP321 occupies 16 bytes each in the I/O areas of the CPU. Communication
between SIWAREX and SIMATIC CPU is supported by the FB.
Table 11-1 Memory requirements of the function block
FB 1, WP321DR
Read weight and status YES
Send commands YES
Send parameters YES
Main memory requirements in CPU 11 600 byte + n x 1 232 byte
Load memory requirements in CPU 138 788 byte + n x 28 470 byte
n = number of WP321 modules
The function block described above including HMI configuring can be downloaded as a
predefined example project ("Ready-for-use") from the Siemens Customer Support.
11.2 Structure of the program "Ready for use"
There is one program for Step 7 Classic and another for TIA Portal. The two programs each
consist of two parts:
● STEP 7 software for the SIMATIC CPU
● WinCC project (integrated in SIMATIC Manager)
All messages are saved as bit information. The message system can thus directly access the
bit fields and display the message texts.
See also
SIWAREX WP321 "Ready for use" (
https://support.industry.siemens.com/cs/ww/en/ps/17799/
dl)
11.3 Advantages of task sharing
The weight is calculated in the SIWAREX module like in a separate electronic weighing system.
However, thanks to integration in SIMATIC, it is possible to directly transfer the weight value to
the PLC program. This results in sensible sharing of tasks: the weighing functions are
performed in the SIWAREX module, while interlocking and signal linking are performed in the
PLC.
SIWAREX "Ready for use" takes over the task of a standardized program in the SIMATIC S7.
SIWAREX WP321
Operating Instructions, 08/2019, A5E33715669A-AD 103
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