====== Single alarm memory ======

{{:en:mervis-ide:35-help:bd49.png}}

===== Block name =====

BD49_SINGLEALARMMEMORY

===== ST call =====

<code st-iec>
PROGRAM TEST_BD49
  VAR
 BOOL1, BOOL2, BOOL3:BOOL;   
    FB : LIB.CORE.V1_0.BD49_SINGLEALARMMEMORY;
  END_VAR

 FB(IN:=BOOL1, RESET:=BOOL2);
    BOOL3 := FB.MEMORY;
END_PROGRAM
</code>

===== Library =====

LIB\CORE

===== Version =====

V1.0

===== Description =====

This block is dedicated to deal with alarm states. The alarm signal is at the //IN// input. A rising edge on the //IN// input sets //MEMORY// to //TRUE// (alarm memory). The alarm can be reset by a rising edge at the //RESET// input. If //IN=FALSE// at the reset time, then //MEMORY// goes to FALSE. If the alarm is active (//IN=TRUE//), it can not be reset by the //RESET//input, but may be acknowledged by a rising edge brought to the //ACK// input.

===== Inputs =====

|Input|Type|Description                                                                                                            |Default value|
|IN   |BOOL|Input of the alarm signal                                                                                              |False        |
|ACK  |BOOL|Acknowledge. If //IN=TRUE// and rising edge comes to //ACK// then //ACKNOWLEDGED=TRUE// (while keeping //MEMORY=TRUE//)|False        |
|RESET|BOOL|Reset of the alarm memory and ACKNOWLEDGED output                                                                      |False        |

===== Outputs =====

|Output      |Type|Description                                                                                                                     |
|ACKNOWLEDGED|BOOL|Indication that an alarm has been acked                                                                                         |
|MEMORY      |BOOL|Alarm memory                                                                                                                    |
|ALRSTATUS   |INT |Status of the alarm block (bit 8 indicates //IN=TRUE//, bit 9 indicates //ACKNOWLEDGED=TRUE//, bit 10 indicates //MEMORY=TRUE//)|

===== Application example =====

{{:en:mervis-ide:35-help:bd49_example.png}}

This alarm is activated by the b1 input. It is not acknowledged (input ACK is not connected), so it can only be reset after //b1// is FALSE again.