Latch Relay (L) - Mitsubishi Electric melsec q00ujcpu User Manual

9.2.4

Latch relay (L)

(1) Definition
The latch relay (L) is a device for auxiliary relays that can be latched inside the CPU module.
Latch relay data are retained by batteries in the CPU module during power failure.
Operation results (on/off information)
• Powering off and then on the CPU module
• Resetting the CPU module
(2)
Latch relay clear
The latch relay is turned off by the latch clear operation. (
the latch relay set in "Latch (2) start/end" in the Device tab of the PLC parameter dialog box
However,
cannot be turned off even by the remote latch clear function.
(3) Allowable number of
There are no restrictions on the number of normally open or closed contacts used in a program, as
long as the program capacity is not exceeded
X0
L0
X1
X2
Scan time is prolonged when the latch relay (L) is used. Reducing the points of latch relay (L) can reduce the prolonging
scan time. (
(4) Method for external output
The output (Y) is used to output sequence program operation results to external devices.
●
If latch is not required, use the internal relay (M). (
●
The latch clear invalid area is set in the Device setting of PLC parameter. (
9 - 10
normally open or closed contacts
SET
TO
Y20
L0
L100
L0
L2047
Figure 9.10 Latch relay
Section 10.1.2)
immediately before the following will be also retained.
Section 3.7)
.
No restrictions on the quantity used.
M0 is set to on when L0 turns on from off.
L0
Latch relay (L0) can be set to on only for
use inside the CPU module, and not for
output to the outside.
K20
The on/off information of L0 is output from the
output module to the external device.
Section 9.2.3)
Section 6.3)