UT_ALARM_TABLE — All of a site's alarms in one block

Every alarm of a project in one array, one row each, with the siren (horn), the
beacon and one status line for the whole site. Each row has its own on and off
delay, warn or trip, and how it clears: by itself, latched until reset, or
retrying a few times and then locking out. The block holds no texts: the HMI shows
the row numbers, states and codes in its own words.

For alarms that need shelving, priorities and time stamps, use
UT_ALARM per alarm with UT_ANNUNCIATOR.

Pins

Number the rows from 1 (ARRAY[1..n]). The row number is the alarm's number for
the HMI and SCADA, and 0 means "none" in first and latest: a row 0 never shows
in the status line. Put the most important alarms in the lowest rows.

Using it

VAR
  AlmTab : UT_ALARM_TABLE;
  Alarms : ARRAY[1..20] OF UT_AT_ALARM;  (* 1 = sump high-high, 2 = pump 1 overload, ... *)
  AlmSt  : UT_ALARM_TABLE_DATA;
END_VAR

IF FirstScan THEN
  Alarms[1].response := UT_RESP_TRIP;
  Alarms[1].onDelay := T#5s;
  Alarms[1].code := UT_F_HIGH_HIGH;
  Alarms[2].response := UT_RESP_TRIP;
  Alarms[2].reset := UT_RST_MANUAL;
  Alarms[2].code := UT_F_OVERLOAD;
END_IF;

Alarms[1].in := SumpHighHigh;
Alarms[2].in := M1.Fault;
AlmTab(Silence := SilenceBtn, Reset := ResetBtn, Alarms := Alarms, Data := AlmSt);
Horn := AlmTab.Siren;
Beacon := AlmTab.Beacon;

One alarm UT_AT_ALARM

Your logic writes in every scan. The settings have working defaults: a row with
only in wired is a warning that sounds the siren and clears by itself.

States UT_AT_STATE

Record UT_ALARM_TABLE_DATA

The commands act once, on their rising edge, and the block clears them. A command
held on (a Modbus coil left on) acts once.

Status

The status line names one alarm: the lowest row with a trip on, else the lowest
row with a warning on. A trip in row 9 beats a warning in row 1. The words are the
prefix and the alarm's code (UT_STATUS_TEXT). The text is
rebuilt only when the code or the fault changes. The numbers are in
conventions.

A row with no code of its own reads condition, e.g. Warning: condition.

How it works

1. Delays. The condition must last onDelay to raise the alarm, and be gone
   offDelay to clear it. Each delay counts from the last change of in, so a
   pulse shorter than onDelay is ignored.
2. Raise. The alarm goes ACTIVE (or LOCKED, below), waits for acknowledging,
   and sounds the siren if its siren is TRUE. latest is set to its row.
3. Clear. When the condition has gone: AUTO and RETRY alarms go to RETURNED until
   acknowledged (or straight to NORMAL if already acknowledged); MANUAL alarms go to
   LATCHED and stay on until Reset.
4. Retry and lockout (RETRY). Each raise is counted (retries) from the first in
   the window. Up to maxRetries raises clear by themselves; the next one within
   retryWindow goes LOCKED and stays on until a Reset with the condition gone.
   When the window has passed, the count starts again. With retryWindow T#0s
   the count clears only on a Reset.
5. Reset (the pin or cmdReset) acknowledges every alarm. For each alarm whose
   condition has gone (and stayed gone offDelay), it also clears retries and
   puts a LATCHED, LOCKED or RETURNED alarm back to NORMAL. Pressed while the
   condition is still there, it only acknowledges.
6. Siren. An alarm sounds while its siren is TRUE, it waits for acknowledging,
   it is not silenced, and its condition is present (ACTIVE, or LOCKED with the
   condition back). So the siren stops on Silence, on Reset, or when the
   condition goes; the beacon stays on until it is acknowledged.
7. Silence (the pin or cmdSilence) silences the alarms sounding now. It does
   not acknowledge them. A new alarm, raised later, sounds again.
8. Re-arm. An alarm whose condition is still present rearm after it was
   silenced or acknowledged waits for acknowledging again and sounds again (if
   siren). T#0s = never.
9. Beacon is on while any alarm is on (q) or waits for acknowledging. It is
   steady: flash a lamp from AnyUnacked if you want one.
10. Response OFF switches a row off: its state is OFF, nothing is annunciated,
    its retries are cleared. Set back to WARN or TRIP, it starts at NORMAL.
11. Changing a LATCHED alarm's reset from MANUAL to AUTO or RETRY puts it back to
    NORMAL.

Invalid settings

• A negative onDelay, offDelay, retryWindow or rearm works as T#0s, with
  Setting: a setting while no alarm is on.
• An unknown response acts as WARN, an unknown reset as AUTO.

Power cut

The block keeps nothing: every alarm starts NORMAL, and a condition still present
raises it again (after onDelay). This assumes the Alarms array is not RETAIN:
a retained array keeps the states with the settings. Write the settings from your
program instead (as in the example).