Absolute Process Instruments APD 7580 Manuel de démarrage rapide - Page 4
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Calibration, Output Test, Operation
Output Calibration
Input and output ranges, if specified on your order, are factory
pre-configured (at 24°C ±1°C).
Front-mounted Zero and Span potentiometers are used to
calibrate the output to compensate for load and lead variations.
Note: Perform the following calibration procedure any time
switch settings are changed.
1. Apply power to the module and allow a minimum 20 minute
warm up time.
2. Using an accurate frequency calibration source such as a
signal generator, provide an input to the module equal to
the minimum input required for the application.
In the most cases the minimum input signal will be 0 Hz.
3. Set the frequency calibration source equal to the maximum
input required for the application. This will typically be
within 10% of the range selected with switches A and B.
4. Adjust the Span pot for the exact maximum output desired.
The Span control should only be adjusted when the input
signal is at its maximum. This will produce the correspond-
ing maximum output signal.
For example: 4 mA for a 4-20 mA output or –10 V for a
±10V output.
5. Repeat adjustments for maximum accuracy.
Sensitivity Adjustment
This multi-turn potentiometer provides an adjustable threshold
level that the incoming signal must overcome before an output
can be produced.
This is used to limit noise and minimize false input signals that
may cause erroneous readings.
When fully clockwise (maximum sensitivity), the input thresh-
old is typically ±25 mV.
In the fully counterclockwise position (minimum sensitivity), the
input threshold is typically ±2.5 volts.
A
A
P
P
BSOLUTE
BSOLUTE
ROCESS
ROCESS
Output Test Function
When the Test button is depressed it will drive the output with a
known good signal that can be used as a diagnostic aid during
initial start-up or troubleshooting. When released, the output
will return to normal.
The Test Cal. potentiometer is factory set to approximately
50% output. It can be adjusted to set the test output from 0 to
100% of the output span. Press and hold the Test button and
adjust the Test Cal. potentiometer for the desired output level.
Input Sensitivity
Adjustment
Output Test Level
Sensitivity
Adjustment
Push to Test
Test Cal.
Output
Test
Output Span
Calibration
Span
Output Zero
Calibration
Zero
APD 7580
Frequency to DC
Isolated Transmitter
I
I
NSTRUMENTS
NSTRUMENTS
Operation
The APD 7580 accepts a frequency input and provides an
optically isolated DC voltage or current output that is linearly
related to the input.
The frequency input to the APD 7580 is capacitively coupled
(to remove any DC component at the input) to a comparator
whose threshold is determined by the setting of the sensitivity
control. The output from the comparator passes through an
opto-coupler to the output stage.
The green LoopTracker
tion that a signal is being sensed by the input circuitry of the
module. The LED illuminates when the input is sufficiently
large to trigger the input comparator depending on the input
sensitivity adjustment.
It also indicates the input signal range by changing in intensity
as the frequency changes from minimum to maximum. If the
LED fails to illuminate, or change in intensity as the frequency
Variable
changes, it may indicate a problem with module power, or
Brightness Input
Input
signal input wiring.
Indicator
Loop
Tracker
Note that it may be difficult to see the LEDs under bright light-
ing conditions.
The red LoopTracker output LED provides a visual indication
Variable
that the output signal is functioning. It becomes brighter as
Brightness Output
Output
the input and the corresponding output change from minimum
Indicator
Loop
Tracker
to maximum.
For current outputs, the red LED will only light if the output loop
current path is complete. For either current or voltage outputs,
failure to illuminate or a failure to change in intensity as the
process changes may indicate a problem with the module
power or signal output wiring.
1220 American Way Libertyville, IL 60048
Phone:
800-942-0315
Fax: 800-949-7502
APD 7580
input LED provides a visual indica-
®
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