Series 39 X (PD)0 pages
Differential Pressure Transmitter
Series PD-39 X
based on two absolute sensors
In applications where the differential pressure is more than 5% of the maximum standard
pressure range, differential pressure measurement with two absolute pressure sensors offers
major advantages over conventional methods of differential pressure measurement (such as
the Series PD-10).
The Series PD-39 X does not measure the differential pressure directly - instead, it uses two
absolute pressure sensors to take the measurement indirectly. As well as reducing costs, this
differential pressure transmitter is also more robust in relation to unbalanced (one-sided) overloading. The differential pressure range should be at least 5% of the standard pressure range.
Each pressure side has two pressure connections, so the PD-39 X is easy to use in pressure
lines.
So that the differential pressure can also be measured exactly if the standard pressure range/
differential pressure ratio is high, this series also features the tried-and-tested microprocessorbased technology that is used in Series 30 X. All reproducible pressure sensor errors (i.e. nonlinearities and temperature dependencies) are entirely eliminated thanks to mathematical error
compensation. The sensor signals are measured with a 16-bit A/D converter, so the individual
standard pressure ranges can be measured to an accuracy of 0,05%FS throughout the entire
pressure and temperature range.
Low Pressure Version
Digital Interface
The transmitters have a bus-compatible two-wire RS485 half-duplex interface which is modelled
on the ”MODBUS RTU”. KELLER offers interface converters to RS232 or USB for use here.
The READ30/PROG30 program and the protocol are freely available. The interface offers these
capabilities:
-tReadout of pressure and temperature values for both sensors. This allows readout of the differential pressure as well as the two standard pressure ranges.
-tCalibration of zero points and amplification.
-tScaling of the analog output to different pressure ranges or units.
-tConfiguration settings such as measurement rate, low-pass (LP) filter, bus address, etc.
-tReadout of information such as serial number, compensated pressure and temperature ranges, etc.
Analog Output
Medium Pressure Version
The analog output is freely scalable via the interface. For flow measurements, the root of the
differential pressure can also be outputted. The calculated value can be outputted via an analog
interface (0…10 V or 4…20 mA).
Series PD-39 X: Low Pressure Version
44
Series PD-39 X: Medium Pressure Version
PIN ASSIGNMENT
Output
26
DIN
43650
MIL
C-264882
OUT/GND
1
1
C
+Vcc
3
3
A
0…10V
70
Binder
723
2-Wire
26
60
Function
4…20mA
44
GND
1
1
C
B
3-Wire
71
64
16
1
22
G1/4”
16
1
2
3
3
RS485A
4
D
ming
ca. 25
2
Program-
ca. 25
OUT
+Vcc
RS485B
5
F
5
24
26
G1/4”
26
Subject to alterations
KELLER AG für Druckmesstechnikt
KELLER Ges. für Druckmesstechnik mbHt
Companies approved to ISO 9001
A
09/2014
St. Gallerstrasse 119t
Schwarzwaldstrasse 17t
CH-8404 Winterthurt
D-79798 Jestettent
Tel. +41 (0)52 - 235 25 25t
Tel. +49 (0)7745 - 9214 - 0t
Fax +41 (0)52 - 235 25 00
Fax +49 (0)7745 - 9214 - 60
www.keller-druck.com