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Handheld Programmer
BIS M-87_
21
Basic Knowledge
4
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” starting
on page 25
).
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 lost.
This leaves 14 bytes per block available. The usable number of bytes can be found in the follow-
ing table.
Balluff data carrier type
Memory capacity
Usable bytes for CRC_16
BIS M-1_ _-
01
752 bytes
658 bytes
BIS M-1_ _-
02
2000 bytes
1750 bytes
BIS M-1_ _-
03
112 bytes
98 bytes
BIS M-1_ _-
04
256 bytes
224 bytes
BIS M-1_ _-
05
224 bytes
196 bytes
BIS M-1_ _-
06
288 bytes
252 bytes
BIS M-1_ _-
07
992 bytes
868 bytes
BIS M-1_ _-
08
160 bytes
140 bytes
BIS M-1_ _-
09
32 bytes
28 byte
BIS M-1_ _-
10
736 bytes
644 bytes
BIS M-1_ _-
11
8192 bytes
7168 bytes
BIS M-1_ _-
13
32786 bytes
28672 bytes
BIS M-1_ _-
14
65536 bytes
57344 bytes
BIS M-1_ _-
15
131072 bytes
114688 bytes
BIS M-1_ _-
20
8192 bytes
7168 bytes
4.7 CRC check