Hi, Not specific to any manufacturer of PLC or HMI/Scada but looking for best approach.
To ensure a HMI/Scada receives the alarm I assume most people latch alarms in the PLC, so I ask.
If you latch the alarm in the PLC when do you unlatch?
If alarm is not latched how do you ensure the HMI receives the alarm?
Thanks in advance.
To ensure a HMI/Scada receives the alarm I assume most people latch alarms in the PLC, so I ask.
If you latch the alarm in the PLC when do you unlatch?
- If an alarm is latched, the HMI will not be able to determine if the alarm condition has gone without operator input, or using handshaking bits for each alarm.
- If operator input is required do you have multiple alarm acknowledge bits for user/areas to prevent users from acknowledging alarms from an area they are not authorised?
- How do you determine how long an alarm condition was active if alarm is latched
- Do you only latch the alarm for xx Seconds?
If alarm is not latched how do you ensure the HMI receives the alarm?
- If alarm is not latched in the PLC, the HMI/Scada could miss alarms due to comms
- HMI/Scada will know alarm condition has gone without operator input
- Alarm active times will be accurate for trending/reporting systems.
Thanks in advance.