Page 5
OPERATION
During normal mode the device reads the pressure sensors and calculates the pressure value depending
on the selected range. The pressure value is displayed on the LCD and set as the output value for the analog
output. The output value is updated once per second.
For normal operation such as 0-100 PSI, the pressure applied to the High port must be higher than the
pressure applied to the Low port. If the pressure connection is reversed then the transmitter will always
output 4 mA. If the Low port is left open to ambient pressure, then the High port is used to measure a
positive pressure and 0 PSI = 4 mA and 100 PSI = 20 mA.
For bi-directional operation such as ±100 PSI, the pressure applied to the High port should be higher than
the pressure applied to the Low port for a positive output response. Negative pressure is indicated if the
High pressure is less than the Low pressure. In this case -100 PSI = 4 mA and +100 PSI = 20 mA. Since the
transmitter is linear 0 PSI = 12 mA.
The output value may be affected by device settings such as the pressure damping time. The pressure
averaging setting controls how many readings are averaged to form the output value. For example, if the
pressure averaging value is set to 30 seconds then 30 one-second readings are stored and averaged to
form the output value. The next second will add a new reading and delete the first to form a new 30 second
average for output. The output gets updated every second with a new average reading. The averaging
value can be set from 1 to 60 seconds via the User Menu.
During normal mode, the device also monitors the <ZERO / UP>, <DOWN> and <MENU> keys and takes
appropriate action. The keys are used to access the User Menu. The device also monitors the Volt/mA
jumper to determine the appropriate output scaling. The voltage span may be set via the User Menu to
either 0-5 Vdc or 0-10 Vdc.
A sensor auto-zero can be initiated by pressing and holding the internal <ZERO> switch for at least 3
seconds. If both pressure ports are close to zero pressure, then the device will calibrate with a new zero
point. The auto-zero can also be initiated by holding the ZERO terminal low for 3 seconds.
Generally, it is not recommended that a span calibration be performed in the field unless a high-quality
calibrator with low differential pressure ranges is available and the temperature of the sensor can be
maintained.
P. Port
Direct
The Pressure Port defaults to Direct (HIGH Port = High Pressure, LOW Port =
Low Pressure). Use <UP> or <DOWN> to change it to Reverse (HIGH Port = Low
Pressure, LOW Port = High Pressure) if it is necessary to swap the ports due to a
plumbing error.
<MENU>
Press to save and advance to next menu item
6. PRESSURE PORT
Output
Direct
The analog output defaults to Direct (4-20 mA, 0-5 Vdc or 0-10 Vdc). Use <UP> or
<DOWN> to change it to Reverse (20-4 mA, 5-0 Vdc or 10-0 Vdc.
<MENU>
Press to save and advance to next menu item
5. OUTPUT
Backlite
Auto
The backlight operation defaults to Auto operation. It can be set to Off or On Auto
using <UP> or <DOWN>. Auto means the LCD backlight only lights when a menu
is accessed, off means it never lights and on means it is always on.
<MENU>
Press to exit and return to normal operation.
7. BACKLIGHT
IN-GE-DPXXX-02-02 11/19
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