resistor positions which you may complete with the proper value components for your
application.
LOW PASS FILTERS DE-BOUNCE INPUTS
A low pass filter is placed on the signal wires between a signal and an A/D board. It
stops frequencies greater than the cut off frequency from entering the A/D board's
analog or digital inputs.
The key term in a low pass filter circuit is cut off frequency. The cut of frequency is
that frequency above which no variation of voltage with respect to time may enter the
circuit. For example, if a low pass filter had a cut off frequency of 30 Hz, the kind of
interference associated with line voltage (60Hz) would be filtered out but a signal of
25Hz would be allowed to pass.
Also, in a digital circuit, a low pass filter might be used to de-bounce an input from a
momentary contact button pushed by a person.
A low pass filter may be constructed from one resistor (R) and one capacitor (C). The
cut off frequency is determined according to the formula:
1
Fc = 2 * Pi * R * C
Where Pi = 3.14...
1
R = 2* Pi * C * Fc
17
RUNNING INSTACAL
TM
To run InstaCal
TM
in the various forms of Windows, find the file named InstaCal.exe
using your file management system and double click your mouse on it. In DOS simply
type instacal and press the Enter key.
Once running, InstaCal
TM
provides four sub-menus (plus exit).
1. Select Install (either highlight it and hit enter or double click your mouse on it).
2. Select Board #0 (select another number if Board #0 is already installed)
3. Select Board Type
4. Move through the selections and highlight the particular board you are installing
(e.g. CIO-CTR05 or CIO-CTR10). Either double click on the board or hit enter.
5. The board’s default settings are then displayed. The board’s defaults are:
BASE ADDRESS:
300H (768 Decimal) Same as data sheet. If
address 300 is not available, choose another and
InstaCal will show you the correct switch setting.
WAIT STATE:
OFF.
6. You are now ready to install the board in your computer. Turn off your computer,
unplug it from AC power, open your PC and install the board in any unused ISA
slot. After the board is installed and the computer is closed up, turn the power
back on.
7. Run InstaCal
TM
again, and at the main menu select Test.
a. Select the board you just installed
b. Select Internal Test
c. The internal control registers of the board will then be tested. If this test
is successful, your board is installed correctly. If not, you likely have
a base address conflict, or have the base address switch set incorrectly.
Please refer to the next chapter for more information regarding selecting
and setting the base address.
d. If the Internal Test is completed successfully, you may want to check
that the I/O pins are working correctly. To check this select
External Test and follow the instruction provided. This will
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