Garmin GEA 71 Manuale di installazione - Pagina 27
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4.2
Electrical Characteristics
4.2.1
Analog Input Configuration
All analog inputs, except those discussed in Section 4.2.3 are multi-purpose capable and have several
configuration options. Table 4-1 summarizes the configuration options.
Configurable Parameter
Resistive Divider
Voltage Measurement Ranges
Bipolar/Unipolar
Constant Current Source
Miscellaneous Sensor
Configuration Parameters
If installing an ungrounded thermocouple to an Analog In input, a dc reference must be
added to the LO input. This can be accomplished by adding a resistance of 1 MΩ or less
between ground and the Analog In LO input that the ungrounded thermocouple is
installed on.
GEA 71 Installation Manual
190-00303-40
Table 4-1. Analog Input Configuration Summary
Resistive Divider can be enabled or disabled for each analog input.
Enabling & Disabling is achieved via software configuration. See
Section 3.6.
When Disabled: Hardware scaling is 1:1 and input impedance is
greater than 10 MΩ.
When Enabled: Hardware scaling is 50:1 and input impedance is
approximately 100 kΩ.
There are six voltage measurement ranges for analog inputs:
•
25 mV, 55 mV, 100 mV, 1 Vdc, 2.5 Vdc, and 5.0 Vdc (Applies
to both 1:1 and 50:1 scaling).
Effective voltage range in 50:1 mode:
•
1.25 Vdc, 2.75 Vdc, 5.0 Vdc, and 50 Vdc.
Each analog input can be configured to measure Bi-Polar (positive
and negative) or Uni-Polar (positive only) voltages. All analog inputs
are differential.
Each analog input can be configured to supply a 250 µA constant
current source (CCS) from the positive differential input used to
measure resistive sensors.
•
Update Rate
•
High Side Current Monitor Feature Enabled/Disabled
•
Voltage Translation Equations
•
Minimum/Maximum Values for Sensors
•
Hysteresis Value
•
Digital Filtering Value
Description/Characteristic
NOTE
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