OBID
®
System-Manual
ID RW40.30-USB
FEIG ELECTRONIC GmbH
Page 38 of 57
H80701-2e-ID-B.doc
4. Polling-Mode (reading and writing of transponder data)
The polling mode is intended for data exchange with transponders.
Before reading or writing any data, a transponder has to be selected. This will be effected by sending
the command [0x11] to the reader (see 4.1. [0x11] Read Serial-No. (selection of transponder)). If a
transponder is within the detection range of the reader it will be selected. All following read- / write
commands will be effective only to this individual transponder. If the transponder changes, the new
transponder has to be selected first. This way the reader secures that all data that have been read
come from the same transponder and also writing of data only is effected on the transponder which
has been selected last.
In case of a reading command the reader carries out a reasonableness check of the data by reading
them two times or by checking the data security-mechanisms like checksums or parity bits. It only puts
out the requested data if the result of the reasonableness check is positive. In case of a negative
result the reader will send a failure status.
After writing the data, these will be read back by the reader and compared to the written data. Only if
the read back data are identical to the written data, the writing procedure will get a positive receipt.
Note:
During the writing of data on a transponder, it has to be secured first that the transponder is
located within the writing range of the reader during the entire process. If the transponder will
be taken out of the detection range of the reader during a writing process, this will cause a loss
of data.
