Measurement Computing CIO-DI48 - Manual (Page 9)

4.0 HARDWARE INSTALLATION
4.1 INSTALLING THE BOARD
1. Turn the power off.
2. Remove the cover of your computer. Please be careful not to dislodge any of
the cables installed on the boards in your computer as you slide the cover off.
3. Locate an empty expansion slot in your computer.
4. Push the b oard firmly down into the exp ansion bus connector. If it is no t
seated fully it may fail to work and could short circuit the PC bus power onto
a PC bus signal. This could damage the motherboard in your PC as well as
the CIO-DI##.
4.2 CABLING TO THE CONNECTOR(S)
The input connector(s) are accessible through the PC/AT expansion bracket. The
connector is a stan dard 50-pin header connector. Cables with mating connectors
(C50FF-#) can be purchased from Measurement Computing Corporation.
Those familiar with the CIO-DIO series boards will find the signal levels and pin
assignments are identical with those on the CIO-DI##.
4.3 DIGITAL SIGNAL CHARACTERISTICS
Inputs are LSTTL (Low power Schotky TTL), a standard for digital signals which are
either at 0V or 5V (nominal).
Low state Near 0V
High state Near 5V
See the electrical sp ecification in this m anual for details regarding logic levels and
maximum voltages allowed at the inputs.
In addition to voltage and load matching, digital signals o ften need to be filtered
(“de-bounced”) to remove spurious false signals from relay or switch contacts . A
description of this filtering method and other subjects on digital interfacing techniques
is in the section on Interface Electronics in this manual.
5