RPM4-AD™ OPERATION AND MAINTENANCE MANUAL
© 2005-2007 DH Instruments, a Fluke Company
Page 106
UNIT
n
Purpose
Read or set the pressure unit of measure unit and measurement mode.
Command
Query
“UNIT
n
unit (, ref
”)”
“UNIT
n
unit
n
(, ref
”)”
“UNIT
n
unit
g
(, ref
”)”
“UNIT
n
unit
a
(, ref
”)”
“UNIT
n
unitd (, ref”)”
“UNIT
n
?”
Classic “UNIT
n
=
unit (, ref
”)”
“UNIT
n
=
unit
n
(, ref
”)”
“UNIT
n
=
unit
g
(, ref
”)”
“UNIT
n
=
unit
a
(, ref
”)”
“UNIT
n
=
unitd (,ref”)”
“UNIT
n
”
Optional Suffix
“n”
The active Q-RPT is assumed if no suffix is given.
‘1’ Specify the Hi Q-RPT if the HL RPT is not active
Specify the HL Q-RPT if the HL Q-RPT is active
‘2’ Specify the Lo Q-RPT if the HL Q-RPT is not active and the
measurement mode is not differential
‘3’ Specify the HL Q-RPT if the HL Q-RPT is active
Arguments
Unit:
ref:
The text corresponding to the pressure unit of measure. A unit mode
character can optionally be added to the end of the units to change the
measurement mode as wel as the units:
‘a’ for absolute measurement mode.
‘g’ for gauge measurement mode.
‘n’ for negative gauge measurement mode.
‘d’ for differential measurement mode (Hi Q-RPT only)
The optional unit reference temperature only if the unit is “InWa” or a true
airspeed.
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.
If the unit text is not followed by an explicit mode character (‘a’, ‘g’, ‘n’ or ‘d’) then the current mode
is retained. There can be a space between the unit text and the ‘a’, ‘g’, ‘n’ or ‘d’.
If the unit specified is “InWa”, an optional second argument “
ref”
can be set. The “ref” can be 4, 20,
or 60 corresponding to InWa at 4 °C, 20 °C or 60 °F. If this second argument is not given when
the unit is “InWa”, then the reference temperature is assumed to be 20 °C.
If the unit specified is a “true” airspeed unit, then an optional second argument “
ref”
can be set.
The “ref” temperature is always in °C. If this second argument is not given, then the reference
temperature is assumed to be 15 °C.
The fifth character of the reply is always ‘a’ for absolute mode, ‘g’ for gauge/negative gauge mode
or ‘d’ for differential mode. White spaces precede this character if needed. The temperature
reference is added to the reply only if the unit is “InWa”. Differential mode is always absolute
differential.
The reply includes the measurement mode character in the fifth position, with an ‘a’ indicating
absolute mode, a ‘g’ indicating gauge or negative gauge mode or a ‘d’ indicating differential mode.
The “MMODE” command can also be used to set the desired measurement mode only. Since
pressure units are mode dependent, the mode desired should be established before the unit is set.
Example
(enhanced)
Cmd sent:
Query reply:
Sent:
Query reply:
Sent:
Query reply:
Sent:
Query reply:
“UNIT? kPaa”
“kPaa”
“UNIT? InWag, 4”
“inWag, 4”
“UNIT? InWaa, 60”
“inWaa, 60”
“UNIT? MACH, 18”
“MACH, 18.0”
Example
(enhanced)
Cmd sent:
Query reply:
“UNIT psi n”
“psi g”
(‘g’ used to indicate both gauge & neg gauge modes)
Example
(classic)
Sent:
Reply:
Sent:
Reply:
“UNIT=kPaa”
“kPaa”
“UNIT=InWag, 4”
“inWag, 4”
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”
3.3.2, 3.3.3, 3.5.6, 7.2
