The Logical Trigger - Siemens SIMATIC NET CP 343-1 ERPC Manual

ERPC functions
6.2 ERPC services and communication
Supplied information
When a read/write job has executed, the following information is returned to the ERP
subscriber by the CP:
● A data record (with read jobs)
● An acknowledgment
6.2.4

The logical trigger

What is the logical trigger?
The event-oriented transfer of data from the process to the ERP subscriber is initiated using
triggers. The 'logical trigger' is supported by the ERPC software.
The logical trigger is a reaction to an event on the S7 controller. The reaction is the reading
out of certain data from the S7-CPU.
Data can only be read from the CPU as a result of the logical trigger. If data needs to be
written to the CPU by a logical trigger, this can be configured in the ILS Workbench as the
follow-on reaction to the trigger data that was read.
The logical trigger is created in the ILS Workbench. The link to the process data is created
during configuration and programming of the S7 controller:
● The function of the logical trigger on the S7 controller is implemented by the software
● The data areas to read out and written to on the CPU are defined using the ERPC
● The condition that decides when the function can be called, on other words, when the
When the S7 station is operational, the ERPC application waits for the logical trigger to be
fired by the user program of the CPU. When the logical trigger is fired, FB56 reads the
relevant values from the CPU and transfers them in a data block to the CP firmware. The CP
firmware transfers the data to the ERPC application which puts together a data frame and
sends it to the ERP subscriber.
Supplied information
When a logical trigger has executed, the following information is returned to the ERP
subscriber by the CP:
● A data record
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The CP replies to every requested read or write job with an acknowledgement that
confirms correct execution of the job or contains an error message. If an error occurs,
and error identified is returned and a diagnostic message is entered in the diagnostic
buffer of the CP.
block FB56.
symbols that are specified in the configuration of the CP.
data can be read out, is set in the user program.
CP 343-1 ERPC
Manual, 03/2010, C79000-G8976-C239-02