Chapter 16 Latch Function; Types Of Latch; Device/Label That Can Be Latched - Mitsubishi Electric FX5 User Manual

16
LATCH FUNCTION
The contents of each device/label of the CPU module is cleared in the cases described below and changed to its default
value.
• At power OFF→ON of the CPU module
• At reset
• A power failure that exceeded allowable momentary power interruption
The contents of each device/label with latch setting will be maintained in case of power failure even in the above-mentioned
cases. Therefore, when the data is managed by continuous control, even if power of the CPU is turned OFF or there is a
power failure that exceeds the allowable momentary power interruption, all data can be maintained and control can be
continued.
16.1

Types of Latch

There are two types of latches, latch (1) and latch (2).
Latch clear range can be set by selecting latch (1) or latch (2).
For latch clearing, refer to Page 120 Clearing of Data of the Latch Range.
16.2

Device/label that can be Latched

The devices and labels that can be latched are described below.
The devices that can be latched
The devices that can be latched are described below.
Device
Internal relay (M)
Latch relay (L)
Link relay (B)
Annunciator (F)
Step relay (S)
Timer (T)/Accumulation timer (ST)
Counter (C)/Long counter (LC)
Data register (D)
*1
Link register (W)
*1
File register (R)
*1 Link register (W) and file register (R) can be latched only when an optional battery is used.
Labels that can be latched
The labels that can be latched are described below.
Label
Global label
Local label of the program block
Local label of the Function Block
16 LATCH FUNCTION
118
16.1 Types of Latch
Specification Method
Specify the latch range
Specify the number of points
Specify the latch range
Specify the latch range
Specify the latch range
Specify the latch range
Specify the latch range
Specify the latch range
Specify the latch range
Specify the latch range
Type
VAR_GLOBAL
VAR
VAR
VAR_OUTPUT
VAR_PUBLIC
Applicable latch type
Latch (1) or Latch (2)
Latch (1) or Latch (2)
Latch (1) or Latch (2)
Latch (1) or Latch (2)
Latch (1) only
Latch (1) or Latch (2)
Latch (1) or Latch (2)
Latch (1) or Latch (2)
Latch (1) or Latch (2)
Latch (1) or Latch (2)
Attribute Data type
RETAIN Basic data type, array, structure