Check Byte; Table 3-6. Reject Bytes (Continued) - CPI Satcom Division VZU-6997 Series Installation, Operation And Maintenance Manual

CHPA SERIES

Table 3-6. Reject Bytes (continued)

ASCII Character
d
f
g
i
3.9.6

Check Byte

(Check byte is under CIF CONFIGURATION as CHECKBYTE.)
Two options are available:
Longitudinal Parity—The check byte is the exclusive OR of all message bytes including the
header and ending bytes and excluding CR or LF if chosen. (LONG on front panel.)
Checksum—This formula provides a printable ASCII checksum. (SUM on front panel.)
N
Checksum = 32 + MOD
i=1
where:
•
MOD is the operation modulo 95.
95
•
N is the total number of bytes in the message including header and ending bytes and
excluding CR or LF if chosen.
• is the ith message byte where 1 ≤ i ≤ N.
message byte
i
Example: Calculate the check byte for the message {A1} using the checksum rule.
Character: { A 1
ASCII: 123 65 49 125
i: 1 2 3 4
Check Byte = 32 + MOD
= 32 + MOD [234]
95
= 32 + 44
= 76 which translates to the ASCII character L
3-12
Decimal Meaning
100 Slow command in execution
102 The command was not executed; high voltage is OFF.
103 The command was not executed; RF is inhibited.
105 The command was not accepted; unit is in Fault.
[(Σ message byte ) – (32 * N)]
i
95
}
[(123+65+49+125) – (32*4)]
95
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D .01023245 R .L
OC EV