KEYENCE Visual KV Series - Manual (Page 102)

2.4 Instruction Details
3-78
2
Chapter 2 Instructions
Example
Coding
Timing diagram (0000, 1000, and 1001 in the above example)
• The DIFU instruction turns ON the relay specified by the operand for only the 1st
scan time at the rising edge of input signal (0000).
• The DIFD instruction turns ON the relay specified by the operand for only the 1st
scan time at the falling edge of input signal (0000).
Note 1: Any DIFU/DIFD operand relay No. cannot be duplicated in a program.
Note 2: When an expanded ladder is used, the DIFU instruction in example a)
operates without any problems. However, with the DIFD instruction in example b),
output relay 0500 does not turn ON because 1000 turns ON at the next scan after
the falling edge of input relay 0000 though input relay 0000 is already OFF. In this
case, change the ladder diagram as in example c).
Operands
* Note that of I/O Nos.7000 to 9915, those that are not assigned to expansion or I/O
terminal module ports can be used for internal utility relays.
Key operation
DIFU: Differentiate Up
DIFD: Differentiate Down:
Detects rising edge of input signal and turns
ON specified relay for 1st scan time only.
Detects falling edge of input signal and turns
ON specified relay for 1st scan time only. nnnn
DIFD
nnnn
DIFU
SET
1
RES
0
RES
0
FUN
FUN
O R
9
0000 1000
DIFU
1001
DIFD
Line No. Instruction Operand
0000 LD 0000
0001 DIFU 1000
0002 DIFD 1001
ON
ON
0000
1000
1001
OFF
ON
0000 1000 1000
DIFU 0500 0000 1000 1000
DIFD
1000
DIFD
0500
0000
1000 0500
a) 0500 turns ON for one scan at the rising edge
of input relay 0000.
c) 0500 turns ON for one scan at the
falling edge of input relay 0000.
b) 0500 does not turn ON for one scan at
the falling edge of input relay 0000.
SET
1
RES
0
RES
0 FUN FUN
O R
9
Operand
(Relay No.)
Operand
(Relay No.)
ENT
R-SRCH
ENT
R-SRCH
ENT
R-SRCH
ENT
R-SRCH
:
:
ON for 1st scan time only
ON for 1st scan time only
DIFU / DIFD
Visual KV KV-300 KV-10/16 KV-24/40/80
1000 to 1915 1000 to 1915 1000 to 1915 1000 to 1915
3000 to 9915 3000 to 6915 3000 to 6915
*7000 to 9915
KVNKA Chap 02_4aP.p65 08.3.11, 11:58 AM 78