BIS V-6106 Ethernet/IP™
Processor Unit
18
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 enabled, a status message will be sent when
a CRC error is detected.
Note
The CRC check function is only supported by read/write heads in the BIS C, BIS VL,
and BIS VM series.
Initializing
To use the CRC check, the data carrier has to be initialized. The data carrier is initialized in the
output buffer using the 12
hex
command identifier. If the data carrier does not contain the correct
CRC, the processor unit sets an error message in the input buffer (see Example 7
on page
73
).
Data carriers as shipped from the factory can be written with a checksum immediately, since all
data is set to 0.
Checksum
M and L system:
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
following table.
C system:
The checksum is written to the data carrier as 2 bytes of information per page. 2 bytes per page
are lost, i.e. the page size is 30 bytes or 62 bytes depending on the data carrier type.
CRC check
6
Startup