UT_VALVE_FLOAT — Floating (3-point) valve or damper

Positions an actuator that only has raise and lower contacts (no positioner),
common on HVAC mixing valves, irrigation and motorised dampers. It estimates the
position from the run time. Position feedback is used if fitted, and the estimate
re-syncs at the ends. Mode, fail action and protections work as
UT_VALVE (UT_VALVE_CORE).

Pins

Record UT_VALVE_FLOAT_DATA (pin Floating)

In the valve record Data: reversalDelay (T#500ms, the pause before changing
direction), position, the modes, the other protections, the HMI commands and the
status.

How it works

• The estimate adds or takes away 100 % × run time / strokeTime while Raise /
  Lower are on. Good feedback replaces it; an end switch sets it to 0 / 100 %.
• A request of 0 % (or 100 %) drives to the end and on for overTravel, then
  stops and doesn't drive again until the request leaves the end.
• A move never lasts longer than strokeTime + overTravel. If it runs out of
  time (stuck, or a move to 0 % / 100 % whose end never comes, e.g. frozen
  feedback), it isn't repeated until the request changes; with feedback the
  deviation warning shows it.
• Power-up: with homeOnStart it homes first in Off and Auto. In Hand it does
  not move: Position is −1, notHomed TRUE, State INVALID, and a new handSp is
  not acted on, until it goes to Auto (it homes, then follows AutoSp), Off or an
  interlock (it homes on the way to the fail position), or the operator sends
  cmdHome (it homes and stays closed, handSp 0). With feedback it starts where
  the feedback says (in Hand it stays there). Without either, in Hand it does not
  move until the operator changes handSp.
• cmdHome at any time re-homes it (a full stroke and the over-travel, then on to
  the request), with the reversal pause if it was raising.
• travelElapsed is how long the move under way has driven; timeLeft its time
  left at the stroke speed (a homing move: the full stroke and over-travel left).
• cmdHome acts once, on its rising edge: one held TRUE homes once.
• OOS and a drive trip: both contacts off.

Status

statusCode, faultId and statusText say the one main thing the valve is
doing, or what holds it back, so a technician can see on the HMI why it is not where
it was asked to be. The most important reason wins: configuration > fault > held /
waiting > warning > position > Off. The words hold no numbers: the target is in demand and the position in position. The time left
(travel, a pause, a fault's recover / retry wait) is in timeLeft. The text is
rebuilt only when the status or the fault changes. Where the valve is (the rows
marked (this block)) comes from the block's last scan, so it shows one scan after
it changes. The numbers are in conventions.

<fault> is faultId, one of: UT_F_BOTH_LIMITS (both limits) · UT_F_ACTUATOR (actuator fault) · UT_F_POS_DEVIATION (pos. deviation) · UT_F_POS_FEEDBACK (position signal).
<setting> with UT_ST_WARN_SETTING is one of: UT_F_SAVE_EVERY (save every) · UT_F_RETRY_WINDOW (retry window) · UT_F_MODE_SOURCE (mode source) · UT_F_DEADBAND (deadband) · UT_F_FAIL_POSITION (fail position) · UT_F_OPEN_THRESHOLD (open/closed limit); with UT_ST_CONFIG one of: UT_F_STROKE_TIME (stroke time, must be above 0) · UT_F_MIN_PULSE (min pulse/overtravel) · UT_F_REVERSAL_DELAY (reversal delay).

Bad settings

A setting that is not a number, negative or unknown never drives the valve somewhere
it could do damage. configBad is set and faultCode bit 8, and faultId names the
setting (the lowest priority). A negative saveEvery keeps nothing; a negative retryWindow
uses the default 1 h; an unknown modeSource uses the HMI (warnings).

• Refused (a fault, both contacts off): strokeTime 0 or less; a negative minPulse,
  overTravel or reversalDelay.
• Warning: deadband negative or not a number (the one-scan travel is used);
  failPosition not a number (stay) or above 100; thresholds not a number (98 / 2).