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5
Technical Information
Analog Interface Description
Analog Interface Description
The Relay 1-4 are controlled by setpoint 1-4: when the measurement
value exceeds the Set Point threshold, the relative Relay is activated.
In particular Relay 4 can be controlled by the fourth set point (Set
Point 4) or by PHD-4 status when the option “Ready SP ON” is
As a factory setting the section “Ready Set Point ON” is activated.
In the first case (Relay 4 control = Set Point 4) the Relay 4 is
activated (closed), when the measurement value exceeds the Set
Point 4 threshold.
In the second case (Relay 4 control = PHD-4 status) the Relay is
activated (closed) only if the unit is in measurement status (open if
unit is in self test, reading adj., sensitivity changing, ecc.).
In the second case (Relay 4 control = Ready) the Relay 4 is activated
when the PHD-4 is ready for the measurement. As a default
condition, “Relay 4 control” is set to “Ready”.
The output of each relay is present on the auxiliary connector (see
the figure "Electrical Connections Table").
A digital input on pin 4 controls the zero function of the PHD-4 from
remote: when the input is open the FIXED ZERO mode is activated
(indication FZ on the display); when the input is closed the
AUTOMATIC ZERO mode is activated (indication AZ on the display).
To use the remote zero control, or analog remote control menu
NOTE
COMMUNICATIONS/REMOTE CONTROL has to be activated.
The analog output on pins 1 and 6 provides an analog voltage
proportional to the Helium concentration. Its output is from -1.25 V
to +5 V according to the following values:
in HS mode: -1,25 V = -18 ppm +5V = 10
in LS mode: 1.25 V = -1800 ppm +4 V = 10
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PHD-4 Portable Helium Detector User Manual / 87-900-120-01 (F )
5
ppm
6
ppm
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