Alarm states
Alarms can assume different states depending on the acknowledgement type. The three status bits (defined by "Status variable" and "Status variable bit number" of the alarm) are set depending on the alarm status. There are six different states that are assumed depending on the selected acknowledgement type:
|
Condition |
State identifier for use in the programme code or in the alarm filter |
Status (bit-coded) |
Description of the |
Acknowledgement type |
|||
|---|---|---|---|---|---|---|---|
|
|
|
|
|
Reset |
Subject to acknowledgement |
Double receipt required |
Not subject to acknowledgement |
|
inactive |
Cleared Note: It is not possible to filter according to this status. |
000 |
The alarm is not active |
x |
x |
x |
x |
|
come |
Active |
100 |
The alarm is active |
x |
x |
x |
x |
|
acknowledged |
ActiveAck |
011 |
The alarm is active. The user has acknowledged the active alarm. |
- 1) |
x |
x |
x |
|
gone |
Inactive |
010 |
The alarm was active but is no longer active. The user has not acknowledged the alarm in the active state. |
- |
x |
x |
- |
|
acknowledged gone |
InactiveAck |
001 |
The alarm was active. The user has acknowledged the alarm in the active state. The alarm is now no longer active. The deactivation of the alarm must be acknowledged again. |
- |
- |
x |
- |
|
reactivated |
Reactivated Note: Filtering is not possible after this status. |
101 |
The alarm was inactive but has become active again without being acknowledged. This status is not static. It is only signalled. The alarm reverts to the "come" status. |
- |
x |
x |
- |
|
1) |
Acknowledging an alarm of this acknowledgement type directly resets the event bit. This assumes that the bit in the PLC is not permanently held in a state. |
The following sequence diagrams result in the acknowledgement:
Acknowledgement type "Reset"
Acknowledgement type "Requires acknowledgement"
Acknowledgement type "Double acknowledgement required"
Acknowledgement type "Not subject to acknowledgement"
The following abbreviations are used in the diagrams above:
|
Abbreviation |
Meaning |
|---|---|
|
B:1 |
Event bit is set (e.g. by the PLC) |
|
B:0 |
Event bit is reset (e.g. by the PLC) |
|
B=0 |
State of the event bit = 0 |
|
B=1 |
State of the event bit = 1 |
|
Q: |
Alarm is acknowledged |