Setting
RFID channels – parameter data
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8.1.3
HF applications – setting the bridging time (bypass time)
Due to the expansion of the HF transmission zone the tag may drop out momentarily during a
write or read operation and then later return again. The period between the dropout and the
return to the transmission zone must be bridged so that the write or read operation is com-
pleted. The bridging time is the time between the dropout and the return to the detection
range. The Bridging time parameter takes up 1 word in the parameter data image and is stated
in ms.
The bridging time can be set between 4…1020 ms. The bridging time parameter depends on
the components used, the write/read distances, the speed of the tag to the read/write head
and other external factors.
The following figure shows the typical characteristics of the detection range and the path
covered by the read/write head. A shows the section to be bridged:
A
Fig. 69: Detection range of a read/write head
Retaining the default setting
The default setting for the bridging time is 200 ms. In HF bus mode the default value is 48 ms.
Retain the default setting: If the commissioning is successful, the parameter does not
have to be adjusted to the application. If the commissioning is not successful, an error
message will appear.
If the error message appears, adjust the bridging time. If the bridging time cannot be
adjusted, reduce the speed or the data volume.
The information “Recommended distance” and “Maximum distance” is provided in the
product-specific data sheet as well as in the RFID engineering manual.
Adapting the bridging time to the application
Measure the required bridging time directly on location. The LEDs of the read/write head
and the TP status bit of process input data indicate whether the tag is in the sensing
range or not.
Enter the required bridging time.