VN-200 User Manual
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5.11.5
SerialChecksum
This field controls the type of checksum used for the serial communications. Normally, the VN-200 uses
an 8-bit checksum identical to the type used for normal GPS NMEA packets. This form of checksum
however offers only a limited means of error checking. As an alternative, a full 16-bit CRC (CRC16-CCITT
with polynomial = 0x07) is also offered. The 2-byte CRC value is printed using 4 hexadecimal digits.
Table 29 – SerialChecksum
Value
Description
0
OFF
1
8-Bit Checksum
2
16-Bit CRC
5.11.6
SPIChecksum
This field controls the type of checksum used for the SPI communications. The checksum is appended to
the end of the binary data packet. The 16-bit CRC is identical to the one described above for the
SerialChecksum.
Table 30 – SPIChecksum
Value
Description
0
OFF
1
8-Bit Checksum
2
16-Bit CRC
5.11.7
ErrorMode
This field controls the type of action taken by the VN-200 when an error event occurs. If the send error
mode is enabled then a message similar to the one shown below will be sent on the serial bus when an
error event occurs.
$VNERR,03*72
Regardless of the state of the ErrorMode, the number of error events is always recorded and is made
available in the SysErrors field of the Communication Protocol Status Register.
Table 31 – ErrorMode
Value
Description
0
Ignore Error
1
Send Error
2
Send Error and set ADOR register to OFF
