Walk up to a running machine and open the alarm view. If there are forty standing alarms and the operator says “those are always there”, the alarm system has already failed — it just has not caused the incident yet.
Design rules that survive production
- Every alarm demands an operator action. If no action exists, it is a log entry or a maintenance message, not an alarm. This single rule eliminates half of most alarm lists.
- Three or four classes, ruthlessly applied: safety/shutdown, fault (machine stopped), warning (intervention soon), information. Color and sound follow class, never individual taste.
- Alarm text states cause and location, not internal signal names. “Exit conveyor motor overload — check jam at discharge” beats “M7 OVL” in every audit and every night shift.
- Suppress consequential alarms. When the main drive trips, forty downstream “no speed” alarms are noise. Group and inhibit by state.
Cleaning up an existing machine
Export the alarm log for a month and sort by frequency. The top ten alarms are typically 80 % of occurrences; fix, re-class or remove them one by one. It is unglamorous work that measurably reduces stops — operators respond to alarms again once alarms mean something.
FAQ
Discrete alarms or analog limit alarms in the PLC? Generate alarms in the PLC (program alarms in S7-1500), not in HMI tag polling — PLC-side alarms are faster, timestamped properly, and survive HMI restarts.
How many alarms is too many? A useful benchmark from process industry standards: an operator should see fewer than one or two alarms per ten minutes in normal operation. Machines deserve the same respect.
Zone Otomasyon audits and redesigns alarm systems during retrofits — often the cheapest availability improvement on the machine. Contact us.