Chapter 2 – Applications
Analog Pressure Output – The DPM generates a linear signal that corresponds to the
measured (actual) space pressure over the range of −0.2 to +0.2 in. of H
2
O (−49.8 to +49.8
Pa) (
Table 1). If the measured pressure is outside this range, the output signal remains at its
minimum or maximum level depending on the direction of the airflow.
Table 1. Analog Output Signal Level
Differential Pressure (in. of H
2
O (Pa)) Analog Output (mA)
−0.2 (−49.8)
4
0.0 (0.0) 12
+0.2 (+49.8)
20
Calibration
The RPTs are calibrated by a manual procedure involving an external calibration device.
During the procedure, differing values of air pressure are applied to the RPTs. The raw
values are read at the DPM and entered into the calibration points in the database.
For further details, including guidelines for developing a calibration schedule, contact your
local Siemens Building Technologies field office.
Application 790: Slave Mode
Application 790 is the slave mode application for the DPM. Slave Mode is the state of the
DPM when it is shipped from the factory. In Slave Mode, the DPM displays
-OFF and the Red
and Green LEDs are OFF; the Horn Silence button and Pressure Mode Key Switch do not
have defined functions.
Using Relay Outputs
In Slave Mode, the contacts of the alarm output will normally be OPEN. If desired, the field
panel can use this relay for local control.
The Horn Silence button is a momentary switch. If desired, the field panel can use this
button. The following table is an example of momentary switch action:
When… Then…
The user presses a button The status of BUTTON 1 (Point 35) changes from OPEN to
CLOSED. The button status will return to OPEN once the
button is no longer depressed.
Siemens Building Technologies, Inc. 11
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