Omron CJ - 12-2004 Manual page 89

Data Check
Application Method
Application Example
1,2,3...
70
turn ON. If they are not the same, the Error End Flag (word (n + 7), bit 02) in
Unit Status will turn ON, and the Status Flag (word (n + 8), bit 04) in the
Results Information will turn ON as a warning.
After writing the data, the Data Check command is executed with a Calcula-
tion processing specification to calculate and write the check code. Before
reading the data, the Data Check command is executed with a Verification
processing specification to verify the check code. This enables detecting inter-
nal data corruption that might occur in the Data Carrier when the data is not
being accessed.
Write stage
Read stage
The following example checks the data in addresses 0010 (hex) to 0012 (hex).
1. Assume that the following data is initially in memory.
2. The Data Check command is executed to calculate the check code for
5 bytes beginning with address 0010 (hex). The CRC Code 5CD6 (hex)
Data written
Check code calculated
Check code verified
Data read
Bit
Address
7
(hex)
000F
0010 1 2
0011 3 4
0012 5 6
0013
0014
0015
Section 5-7
Bit
0