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BIS C-87_
Handheld Programmer
19
4.6 Data carrier
types
4.7 CRC check
The following data carrier types are available for the BIS C-87_ Handheld Programmer. Depen-
ding on your selection, either all or only particular data carriers can be processed.
Data carrier Data
BIS C-1xx-04 511 bytes of user data (read/write), 32-byte page size (read-only).
BIS C-1xx-05 1023 bytes of user data (read/write), 32-byte page size (read-only).
BIS C-1xx-11
2047 bytes of user data (read/write), 64-byte page size (read-only)
BIS C-1xx-32 8192 bytes of user data (read/write), 64-byte page size (read-only)
The CRC check is a procedure for determining a check value for data in order to be able to
recognize transmission errors. If the CRC check is activated, an error message is sent when a
CRC error is detected.
Initializing
To use the CRC check, the data carriers must be initialized ( see "Initializing data carriers" on
page 24 ).
If the data carrier does not contain the correct CRC when reading or writing, the Handheld
Programmer sends the error message 'CRC Error'.
Data carriers as shipped from the factory can be written immediately with a checksum, since all
data are set to 0.
Error message
If an error message is the result of a failed write job, the data carrier must be reinitialized to –
make it usable again.
If an error message is not the result of a failed write job, the one or more memory cells in the
–
data carrier is likely defective. The data carrier must be replaced.
Checksum
The checksum is written to the data carrier as 2 bytes of information. 2 bytes per block are
sacrificed. This leaves 14 bytes per block available. The usable number of bytes can be found in
the following table.
Data carrier type Memory capacity Usable bytes for CRC_ 16
BIS C-1xx-04 511 bytes 450 bytes
BIS C-1xx-05
1023 bytes 930 bytes
BIS C-1xx-11 2047 bytes 1922 bytes
BIS C-1xx-32 8192 bytes 7936 bytes
4
Basic knowledge