Teledyne HASTINGS 2002, Инструкция по эксплуатации, Страница: 10 / 49

page 10
Scientific Notation
The Model 2002 measures pressure spanning more than seven decades. In order to easily display
these readings, Hastings Instruments has employed scientific notation. In scientific notation, the
mantissa (the fixed point part) is multiplied by some power of 10 (given by the exponent).
Powers of 10
10
3
= 1000 10
-1
= 0.1
10
2
= 100 10
-2
= 0.01
10
1
= 10 10
-3
= 0.001
10
0
= 1 10
-4
= 0.0001
As an example: 7.60 x 10
+2
Torr
mantissa exponent
"7.60 multiplied by 100" = 760 Torr which is one atmosphere of pressure.
3.2 Run Mode
Normal Operation
The Model 2002 will automatically enter RUN mode upon start-up. This is the mode for normal
operation and the mode in which the instrument will typically spend most of its time. In the run
mode the Model 2002 unit will continuously monitor the pressure and update the alarm conditions
at the speed of the A/D converter and will update the display about four times per second.
A/D Speed Adjust
The Model 2002 utilizes a 24 bit sigma-delta analog to digital converter. This type of converter
averages the input over time to reject interference. Longer averaging times result in more accurate
readings. Increasing the A/D speed will respond to sudden pressure changes faster.
While in the RUN mode, the user can adjust the A/D speed of operation from about 10 Hz to 1000
Hz. At start-up, the instrument will be operating with an A/D frequency of about 60 Hz. The speed
can be adjusted two steps faster. Each step will increase or decrease the A/D frequency by a factor
of two.
In RUN mode, pushing the up arrow will speed up the A/D converter one step and decrease the
response time until the limit is reached (3 steps max). Pressing the button after the limit is reached
has no effect. There will be no indication of the operating speed other than the least significant
digits of the display will tend to run at higher speeds. This will result in a faster triggering of alarms
or relays if a sudden catastrophic failure occurs.
Pushing the down arrow will slow down the A/D converter and increase its accuracy. This will
improve the ability to resolve low pressure readings. If a certain speed is desired, press the up or
down arrows three times and then press the other arrow to select the other speed.
EEPROM Calibration Restoration
There are interlocks built into the CAL mode to minimize the chance of accidental alteration of the
calibration coefficients, but if calibration alteration does occur, the EEPROM calibration data can be
restored in the RUN mode by pressing the up and down arrows simultaneously (Run light will
flash), then press the “ZERO” button, up and down arrow buttons simultaneously. To permanently
restore the factory calibration, press the mode switch enough times to cycle through all of the
operating modes and back to RUN.
This will not correct the calibration if the tube has become contaminated or damaged. This reset
will not affect the gas selection, units or setpoints.
{