Siemens SIMATIC MV440 Operating Instructions Manual page 97

A typical example of the use of XMATCH it is a manufacturing process in which packaging is
printed with individual information:
● Use by date
● Serial number
● Manufacturing location etc.
The information can be represented both as 1D/2D code or as plain text. The task of the
reader is to check that the printing is correct and readable.
A match string is assigned using the three indexes trigger ID, program number and ROI ID
(OCR) or code index ("Read code").
Synchronization is achieved with a trigger ID. The trigger ID is a counter of the external
trigger signals. This counter is reset to "1" by the reader at the start of processing mode,
when there is a program change, and following an error.
The match strings are buffered. The match string buffer has the following size:
● Maximum of 200 KB with SIMATIC MV440 readers
● Maximum of 100 KB with SIMATIC MV420 SR-P
At the same time, it is also possible to buffer in advance:
● A maximum of 20 trigger IDs with SIMATIC MV440 readers
● A maximum of ten trigger IDs with SIMATIC MV420 SR-P.
With XMATCH, you can also send match strings with a "permanent flag" that become valid
starting at the next trigger or after a specific trigger ID.
Up to two permanent settings (XMATCH with permanent flag) can be buffered. If a third
permanent setting is received, the last received setting is overwritten.
Example
If the permanent buffer is empty, XMATCH commands with a permanent flag are received
with the trigger IDs 50, 150, and 100 one after the other. The buffer then contains the
corresponding match strings for the trigger IDs 50 and 100.
Availability of XMATCH
The availability of XMATCH depends on the image acquisition mode.
● With single trigger, autotrigger with initial trigger and scanning, the full functionality of
XMATCH is available.
● In the image acquisition mode "autotrigger" (no external trigger signal), XMATCH can
only be used with a permanent flag and trigger ID "0". This means that the new match
strings are valid starting at the next image acquisition.
Logging the received match strings
If enabled under Options/Diagnostics&Monitoring ("Match string frames" checkbox selected),
the match strings in the diagnostic data sets will also be logged.
SIMATIC MV420 / SIMATIC MV440
Operating Instructions, 04/2013, A5E02371045-06
4.4 Options for image acquisition and image processing
Image processing
95