DH Instruments PPC4, Operation And Maintenance Manual

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PPC4™ OPERATION AND MAINTENANCE MANUAL
© 2009 DH Instruments, a Fluke Company Page 172
UNIT
Purpose Read or set the pressure unit of measure unit and measurement mode.
Command
Query
“UNIT unit (, ref ”)”
“UNIT unit g (, ref ”)”
“UNIT unit a (, ref ”)”
“UNIT?”
Classic “UNIT= unit (, ref ”)”
“UNIT= unit g (, ref ”)”
“UNIT= unit a (, ref ”)”
“UNIT”
Arguments unit:
ref:
The text corresponding to the pressure unit of measure.
The optional unit reference temperature only if the unit is “InWa”.
Remarks This program message determines what unit of measure and what measurement mode is
used to display pressure values. Refer to Table 13 for a detailed list of the units available
and their labels.
The unit text must be followed by ‘a’ if absolute measurement mode is desired, or gauge mode
is assumed. The unit text can optionally be followed by a ‘g’ to specify gauge measurement
mode. There can be a space between the unit text and the ‘a’ or the ‘g’.
If a water column unit (inH2O, mH2O, mmH2O) is specified for the pressure unit of measure,
an optional second argument “
ref” can be set. The “ref” can be 4, 20, or 60 corresponding to
InH2O at 4 °C, 20 °C or 60 °F. The reference temperature can also be added directly onto
the end of the
Unit argument or “@” plus the reference temperature if desired (“inH2O4”,
“inH2O@4”, “inH2O20”, “inH2O@20”, “inH2O60”, or “inH2O@60 corresponding to inH2O at
4 °C, 20 °C or 60 °F). If a temperature reference is not specified, when the unit is “InH2O” or
“mmH2O”, then the reference temperature is assumed to be 20 °C.
Note
The legacy units inWa, mWa and mmWa have been replaced by inH2O, mH2O
and mmH2O in the PPC4 and in documentation. The unit command and
others such as ARANGE continue to support the former “xxWA” units. The
conversion factors are identical.
The fifth character of the reply is always ‘a’ for absolute mode, or ‘g’ for gauge mode. White spaces
proceed this character if needed. The temperature reference is added to the reply only if the
unit is “InWa” or “mmWa”.
“MMODE” must be used to set the measurement mode to negative gauge. The “MODE”
command can also be used to set the desired measurement mode only.
Example
(enhanced)
Cmd sent:
Query reply:
Sent:
Query reply:
Sent:
Query reply:
Sent:
Query reply:
“UNIT kPaa”
“kPaa”
“UNIT InH2Og, 4”
“inH2Og, 4”
“UNIT InH2Og60”
“inH2Og, 60”
“UNIT InH2O@20”
“inH2Og, 20”
Example
(classic)
Sent:
Reply:
Sent:
Reply:
Sent:
Reply:
“UNIT=kPaa”
“kPaa”
“UNIT=InH2Og, 4”
“inH2Og, 4”
“UNIT=InH2Og@20”
“inH2Og, 20”
Errors ERR# 7:
ERR# 6:
ERR# 20:
The unit is invalid.
The ref is invalid.
Absolute measurement mode and altitude units are not allowed with a gauge Q-
RPT.
See Also “MMODE”, “MODE”
3.2.10, 3.2.11