Programming in SIMATIC STEP 7
SIWAREX FTA
DS39 can only be written to if the calibration switch is open – you may therefore
need to recalibrate an already calibrated weighing instrument.
The SIMATIC HMI device can be connected with the MPI or to
PROFIBUS/PROFINET. The calibratable display of the weight value can be
connected to any position in the system hierarchy. The connection does not have
to be sealed and future planning for operator windows are also not influenced by
the calibratable weight display.
8.6.1 Functionality of the calibratable weight display
The value for the calibratable weight display is generated internally by the
SIWAREX FTA, it is encoded and then provided in the data record DR 35 for the
user.
The DR 35 data record is read by the FB SIWA_FTA and is put in the scale DB just
like every other data record in a defined address.
Using the DR 35, the DR39 and variable Variable d_intern_ocx, a common
recognition monitoring of the SecureOCX and the SIWAREX firmware is
guaranteed.
Dataset DR39 must contain the version number (ID) of the calibratable display.
This depends on the used WinCC flexible version.
For the evaluation, an AddOn is used for WinCC flexible – a special function, which
is able to decode the contents of the DR 35 and display it in a special output field.
This AddOn is called “SecureOCX” and must be installed in addition to WinCC
flexible.
If the incoming data is incorrect, ERROR 1 is output.
If data record DR35 is not updated (monitoring time approx. 2 s), instead of the
weight value, the text ERROR 2 appears on the screen.
Errors during mutual detection of SIWAREX firmware and “SecureOCX” generate
ERROR 3 if Regulations=OIML is set. The current weight value is displayed if
Regulations=---- is set.
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