α
2 Simple Application Controllers
Function Blocks 6
6 - 9
6.4
Set/Reset Block
The function block will set or reset an output according to the input condition. When the SET
input is energised, the Output is ON. When the RESET input is energised, the Output is OFF.
When both inputs are energised simultaneously, the Output will follow the Priority Setting
signal. A latched Output does not depend on the constant signal to retain its status.
Set Priority
- When the Set input comes ON, the Output comes ON and remains ON until the
Reset pin receives a signal. Once the Output is ON, the Set input signal can turn OFF without
effecting the Output. If both the Set and Reset pins are ON, the Output is ON.
Reset Priority - The operation is the same as the Set Priority except that when both pins are
ON, the Output is OFF.
Table 6.5: Set/Rest Function Block
1 ) Operation of reset priority
2 ) Operation of set priority
Function
Set Item
Description
S
Set pin for the function block
R
Reset pin for the function block
FB
Allocates priority to either the set or reset function when both pins are
ON
Output
The output of the function block operates in either an ON or OFF
state.
1) Set the output ON until the reset pin is ON.
2) Decides the status of the output depending which input pin has
priority.
0
0
0
R
S
O
S
R
P
ON
OFF
OFF
ON
ON
OFF
Input pin S
Input pin R
Output
ON
OFF
OFF
ON
ON
OFF
Input pin S
Input pin R
Output
