F:\MARKETING\TECHNICAL MANUALS\Air Samplers\DF Battery TECH MANUALS\DF-75 LPM SERIES.doc
Tel: (352) 680-1177 / Fax: (352) 680-1454 / Email: [email protected]
14
RS232 Communications Port
General
Most models of the Digital Flowmeter have the RS232 communications port enabled.
The DFM transmits a fixed length, comma delimited ASCII string of data. The data string is comprised
of the following parameters in its general format.
dd.hh.mm,ttt.t.F,bb.bb.In Hg, dd.dd In H
2
O (aaaaaaaaa or ccccccccc), uuuuu,
[….],vvvvvvvvv,UUU
Where:
dd,hh:mm
-
elapsed time in day.hour: minute format
ttt.t. T
-
temperature [ºF] or [ºC]
bb.bb. InHg
-
barometric (inlet) pressure [InHg] or [mm Hg]
dd.dd InH
2
O
-
differential pressure [InH
2
O] or [mm Hg]
aaaaaaaaa
-
ambient flow with 3, 2 or 1 decimal digit resolution up to
99999, or in x.xxxEyyy format for larger numbers. This
format ensures the possible best resolution even for large
values. Ambient flow has an “a” as prefix
ccccccccc
-
corrected flow (same format as for the ambient flow) but
it has an “S” prefix
uuuuu
-
Engineering Unit for flow: SCFM, SLPM, sccm or
SCMH or aCFM, aLPM, accm or aCMH if ambient flow
is selected
[…]
-
optional values for Totalizer model
vvvvvvvvv
-
Total volume (same format as for the ambientflow)
UUU
-
Engineering Unit for total volume: SCF, SL, scc or SCM
or aCFM, aL, acc or aCMH
The engineering units change according to customer selection. The […] data (total flow and
engineering units are sent out when the Totalizer option is enabled.)
An example of a data string utilizing English units is illustrated below.
0.00:21,77.2 F, 30.74 InHg, 2.98 In H
2
O, 2.72SCFM, 50.21SCF
Data transmission frequency is operator selectable at once per second, once per minute, once per 6
minutes, and once per hour from the serial port.
