KEYENCE Visual KV Series - Manual (Page 35)

1.3 Device Configuration
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1
1
Chapter 1 Programming
1.3.6 Internal Utility Relays
In a relay circuit, when one relay contact is used twice or more inside the circuit, a
multi-pole relay with the same number of poles as the number used may be needed.
Internal utility relays function only in programs, and eliminate the complexity of relay
circuits to facilitate circuit design.
Note 1: Internal utility relays function as contacts and relay coils in programs.
Note 2: There is no restriction of the contact type (N.O. or N.C.) used, the order the
relay Nos. are used, or the number of relays used.
Retentive function of internal utility relays
Except for internal utility relays, all relays turn OFF when the operation mode is
changed or when operation is stopped via a power shutdown. When operation is
restarted, all relays remain OFF except relays whose input condition is ON. How-
ever, internal utility relays can be set using the MEMSW (memory switch) whether or
not they are to be retained. (Internal utility relays 2700 to 2715, however, are always
retained.)
When an internal utility relay is set to be retained, its ON/OFF status is stored even if
the power is turned off. By using the retained relay all clear function (FUN65), all
relays which are set to be retained can be set to OFF.
➮ For more about setting the memory switch, refer to "MEMSW instruction" (p.3-92).
Application example of a retentive function: Lift vertical movement control
Internal utility relays 1000 and 1001 are set to be retained.
When the upper/lower limit switch turns ON, the direction of lift movement is
inverted. Even if the power is turned off while the lift is moving up (or down), the lift
continues to move up (or down) when the power is turned on again.
Note: The retentive function is effective only when internal utility relays retained by
the self-retentive circuit or the SET/SFT/KEEP instruction are also retained by the
memory switch.
Internal utility relays are not retained in the program shown below.
(0000)
(0500)
(0501)
(0001)
0000 1000 0001
T000 0500 0501
T001 0501 0500
1000 #00010
T000
0001 1001 0000
1001 #00010
T001
END
ENDH
MEMSW
$0004
Move-up
Upper limit
switch
Lower limit
switch
Move-down
0000 1001
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