Delta DVP-ES2 - Manual (Page 351)

3 . I n s t r u c t i o n S e t
3 - 2 3 5
API Mnemonic Operands Function
84 CCD P Check Code
Controllers
ES2/EX2 SS2 SA2
SE
SX2
Bit Devices Word devices Program Steps Type
OP X Y M S K H KnX KnY KnM KnS T C D E F
S * * * * * * *
D * * * * *
n * * *
CCD, CCDP: 7 steps
PULSE 16-bit 32-bit
ES2/EX2 SS2
SA2
SE
SX2 ES2/EX2 SS2
SA2
SE
SX2 ES2/EX2 SS2
SA2
SE
SX2
Operands:
S: source data D: Destination device for storing check sum n: Number of byte (n = 1~256)
Explanations:
1. This instruction performs a sum check for ensuring the validity of the communication data.
2. 16-bit conversion: If M1161 = OFF, n bytes of data starting from low byte of S will be summed
up, the checksum is stored in D and the parity bits are stored in D+1.
3. 8-bit conversion: If M1161 = ON, n bytes of data starting from low byte of S (only low byte is
valid) will be summed up, the check sum is stored in D and the parity bits are stored in D+1.
Program Example 1:
1. M1161 = OFF, 16-bit conversion.
2. When X0 = ON, 6 bytes from low byte of D0 to high byte of D2 will be summed up, and the
checksum is stored in D100 while the parity bits are stored in D101.
X0
CCD D0 D100 K6
M1000
M1161
0 0 0 0 0 1 1 1 1 1 0 0 0 0 1 0
0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1
D100
D101 Parity
D0 low byte
D0 high byte
D1 low byte
D1 high byte
D2 low byte
D2 high byte
D100
D101
(S) Content of data
K100 = 0 1 1 0 0 1 0 0
K111 = 0 1 1 0 1 1 1 1
K120 = 0 1 1 1 1 0 0 0
K202 = 1 1 0 0 1 0 1 0
K123 = 0 1 1 1 1 0 1 1
K211 = 1 1 0 1 0 0 1 1
K867
0 0 0 1 0 0 0 1 The parity is 1 when there is an odd number of 1.
The parity is 0 when there is an even number of 1.
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