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Lake Shore Model 421 Gaussmeter User’s Manual
3-10
Operation
ALARM AND RELAY (Continued)
The Model 421 has a single relay that is associated with alarm operation. The relay changes to its
active state when the alarm is active and remains in its normal state when the alarm is not active. Relay
terminals are located in a detachable terminal block on the instrument rear panel as described in
Paragraph 2.7.
The following example details operation with the
Alarm Outside
setting. For example, if the reading is
to be centered on 1 kG, with the high alarm point at 1.5 kG and the low alarm point at 0.5 kG, the
following diagram illustrates when the alarm would be active or normal.
0 kG
+1 kG
+2 kG
+3 kG
3 kG
2 kG
1 kG
Low Alarm
Point
High Alarm Point
Alarm
On
Alarm
Off
Alarm
On
Alarm
Off
Alarm
On
Example of operation
with alarm triggered by
readings OUTSIDE
user defined setpoints.
The following example details how the alarm operates in the
Alarm
Inside
setting. The alarm inside
setup is useful in situations where the user is looking for an indication of a good reading, such as
incoming inspections. For example, you may be sorting a number of 1 kG magnets. The magnets have
an acceptable tolerance of ±0.25 kG. With the high alarm point set to 1.25 kG and the low alarm point
at 0.75 kG, the following diagram illustrates when the alarm would be active or normal.
0 kG
+1 kG
+2 kG
+3 kG
3 kG
2 kG
1 kG
Low Alarm
Point
High Alarm Point
Alarm
Off
Alarm
On
Alarm
Off
Alarm
On
Alarm
Off
Example of operation
with alarm triggered by
readings INSIDE user
defined setpoints
.
3.10 ANALOG OUTPUTS
There are two analog outputs available on the rear panel of the Model 421. They are the Corrected and
Monitor Analog Outputs. Both outputs use BNC connectors with the center conductor carrying the
signal and the outer portion the ground.
The Corrected Analog Output is a DC value proportional to the displayed field. The displayed field
reading is corrected for probe nonlinearity and zero offset. This output is not a real time signal, but is
updated at the same rate as the display. The range of the Corrected output is ±3 volts equals ± full
scale for the selected range.