α2
Simple Application Controllers
Function Blocks 6
6 - 50
6.21 Retentive Alternate Block
This block is equivalent to the Alternate Function block described in section 6.4 but includes a
the retention function. When the retention function is ON, the Retentive Alternation (RAL)
output will act as a latched output and remember the ON/OFF settings in the case of a power
failure. Every time the input pin receives a signal the ALT Output changes its ON/OFF status.
The Output alternates turning ON and OFF.
A Clear input signal over-rides the input signal and turns the Output OFF.
Table 6.21: Retentive Alternate Function Block
Retentive Alternation time chart
Function
Set Item
Description
I
Input pin for retentive alternate function block
C
Clear input pin resets the state of the output regardless of the input
given
FB
Retentive alternation of the output status
Output
The output is affected in the following operation:
1) Reverse the ON/OFF state of the output whenever the input sig-
nal’s ON/OFF operation to the input pin is turned ON (ON to OFF or
OFF to ON)
2) The clear selection resets the output regardless of the input given.
3) Remember Output Signal after a Power Cut
0 0
0
L
A
O
I
C
R
Input pin
OFF ON
Clear pin
Stop mode
(Power OFF)
Run mode
OFF ON
Keep ON/OFF
state of Output pin
Run mode/
Stop mode
(Power OFF)
Output pin
