UT_VALVE_CORE — What every valve block shares

The record, safe-position decision, every protection, fault codes, the status and
the retained stroke count of the valve blocks. Each valve block is this core plus
its own way of moving the valve: the core decides whether the valve follows
its request or goes to the safe position; the valve block decides how (which
outputs, for how long) and reports the fault conditions it sees through the
cause pins. Use it directly only to build a new kind of valve block.

The core is two functions, not a function block:

• UT_VALVE_RESET: the reset request and the retry window of this scan. Call it first.
• UT_VALVE_CORE: everything else.

A function keeps no instance of its own, so the valve record is never copied. The
valve block keeps the core's working state in one UT_VALVE_ST and passes it, with
the record, to both functions every scan. The valve block also runs its own
UT_MODE_SELECT and passes the mode in, and keeps the retained
stroke count (Saved).

Pins

UT_VALVE_RESET

UT_VALVE_CORE

The core's results are in St after the call, for the valve block to read:

The other fields of UT_VALVE_ST are the core's own memory: leave them alone, and
don't show them on an HMI. The variants' own commands (cmdPos on UT_VALVE_3POS,
cmdHome on UT_VALVE_FLOAT) are read by the valve block from its own record.

Status

The core works out statusCode, faultId and statusText for every valve block
(statuses in each block's doc, e.g. UT_VALVE): configuration,
faults, out of service, the interlock and the wait for a new Auto command are its
own; the valve block says where the valve is through VarStatus (worked out from
its last scan, so it shows one scan late). It also reads and clears cmdOpen,
cmdClose and cmdStop (each on its rising edge; a command left in the record at
power-up never acts), keeps stopReason, the last trip and trips, and sets
timeLeft to the time the status shows.

The words hold no numbers: the position or target is in the record (position,
and the variant's targetPos, actualPos or demand), and the time left of a
move or a pause in timeLeft.

The settings are named with UT_FAULT members. The core's own are
UT_F_SAVE_EVERY, UT_F_RETRY_WINDOW and UT_F_MODE_SOURCE (warnings). The valve
blocks' are UT_F_VALVE_TYPE, UT_F_TRAVEL_TIME, UT_F_REVERSAL_DELAY,
UT_F_PULSE_TIME, UT_F_SAFE_POSITION, UT_F_THREE_POS_TYPE, UT_F_MID_TIME,
UT_F_OUTPUT_MIN_MAX, UT_F_RAMP_RATE, UT_F_SHUTOFF, UT_F_FAIL_POSITION,
UT_F_OPEN_THRESHOLD, UT_F_RAW_MIN_MAX, UT_F_DEADBAND, UT_F_STROKE_TIME,
UT_F_MIN_PULSE and UT_F_RATE_UNIT. The full list is in
conventions.

Retained

The mode (in UT_MODE_SELECT) and a snapshot of strokes,
copied every saveEvery (T#0s = not kept) into the valve block's Saved.