UT_UNIT_CONV — Engineering unit conversion (function)

Converts a pressure, flow, volume, temperature or length from one unit to
another: bar to psi, L/s to m³/h, °C to °F. UT_UNIT_OK tells you whether two
units can be converted.

Pins

SuctionPsi := UT_UNIT_CONV(In := SuctionBar, FromUnit := UT_UNIT_BAR, ToUnit := UT_UNIT_PSI);
FlowM3h := UT_UNIT_CONV(In := FlowLps, FromUnit := UT_UNIT_LPS, ToUnit := UT_UNIT_M3H);

UT_UNIT_OK

Units (UT_UNIT)

UT_UNIT_NONE (the default) is "no unit".

How it works

• Different kinds can't be converted (bar to L/s), and neither can NONE. The
  value then comes back unchanged. The function never returns NaN for a wrong
  pair: a NaN makes every comparison downstream FALSE, so a high-level alarm fed
  from it would never trip, and nothing would show why. An unchanged value is
  wrong in a way you see at commissioning. Where the units are chosen at run
  time (from an HMI), check the pair with UT_UNIT_OK and raise your own
  warning.
• The same unit on both sides gives In back exactly.
• Worked in LREAL, so converting there and back loses nothing a REAL can show.
• NaN in gives NaN out; a result beyond the REAL range (about 3.4E38) is infinite.
• US gallons (3.785411784 L). Imperial gallons are not offered.