Setra System Model 470 - Manual (Page 14)

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3. The transducer deselects the engineering units currently in use, and selects the next
engineering units in the sequence:
hPa hectopascals
PSI pounds per square inch
mbar millibar
mm Hg millimeters of mercury
in Hg inches of mercury
mm H2O millimeters of water
in H2O inches of water
ft feet
m meters
units user definable units
4. If you have disabled any of the engineering units using the function described in Section
5.3, those units are ignored. The transducer selects the next engineering units in the se-
quence which are not disabled in response to the U command.
On power-up the 470 will report pressure in the factory default pressure units, unless you
have executed the DISABLE UNITS function (Section 5.3) and omitted the factory default
pressure units from the rotation. In this case, on power-up the 470 will report pressure in the
next engineering units in the rotation which you have not disabled.
4.3 User Defined Engineering Units in Nonvolatile Memory
In addition to the built-in engineering units conversions described in Section 4.2, you can enter a
conversion factor to convert any of the built-in units to any other pressure units.
Engineering units can be directly changed by entering a multiplier (number to multiply by) or a
divisor (number to divide by), and a series of characters to indicate the name of the engineering
units.
The conversion ratio is saved and used for the user-definable engineering units until a new ratio
is entered, even if the power is shut off and turned back on.
1. Use the CONVERT function (see Section 4.2) so that the 470 reports data in units of
pressure in response to an interrogation. (i.e., the transducer should not be reporting in units
of altitude.)
2. Calculate the desired conversion ratio.
3. Determine if the ratio is a multiplier or a divisor. If the ratio is in “units” per hPa, “units”
per PSI, “units” per in Hg, “units” per mbar etc., the ratio is a multiplier. If the ratio is in hPa
per “units”, PSI per “units”, in Hg per “units”, mbar per “units”, etc., the ratio is a divisor.
4. Use the CONVERT function so that the Setra 470 reports the units from which the ratio
was calculated.
5. Set the program enable switch to “ON” (Section 7.2).
6. If the ratio is a divisor, transmit -, the minus symbol.
7. Transmit the conversion ratio.
8. Transmit U, for convert.