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4.2.6
Edge relay (V)
The edge relay (V) is a device in which the on/off information of contacts from the beginning of the ladder block is
memorized. The device can be used only as contacts (cannot be used as coils).
(1) Applications of the edge relay
The edge relay can be utilized to detect the leading edge (off to on) in programs configured using
index modification
[Ladder example]
SM400
X0Z1 V0Z1
SM400
*1
The on/off information for X0Z1 is stored in the V0Z1 edge relay.
For example, the on/off information of X0 is stored in V0, and that of X1 is stored in V1.
[Timing chart]
When Z1=0
When Z1=1
(2) Precautions
The edge relay of the same number cannot be used more than one time in a program.
X0
X1
X10
V1
.
MOV K0 Z1
FOR K10
*1
*1
M0Z1
INC Z1
NEXT
ON
X0
OFF
ON
OFF
V0
ON
M0
OFF
1 scan
X1
OFF
V1
OFF
M1
OFF
Stores on/off information of
X0, X1, and X10.
Clears index register (Z1).
Specifies the number of repeats (10 times).
Turns on M0Z1 1 scan,
followed by rise of X0Z1.
Increments index
register (Z1). (+1)
Returns to FOR instruction.
ON
ON
Turns on for 1 scan by rise of X1.
ON
1 scan
CHAPTER 4 DEVICES
4
355
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