Omega Engineering DIGITAL INPUT/OUTPUT PCI-DIO96 - Manual (Page 9)

3.3 SIGNAL CONNECTION CONSIDERATIONS
All the digital inputs on the PCI-DIO96 are 8255 CMOS TTL. The PCI-DIO96
output signals are 8255 CMOS.
OMEGA Engineering Inc. offers a wide variety of digital signal conditioning
products that provide an ideal interface between high voltage and/or high current
signals and the PCI-DIO96. If you need control or monitor non-TTL level signals
with your board, please refer to our catalog or our web site for the following
products:
CIO-ERB series, electromechanical relay output boards
CIO-SERB series, 10A electromechanical relay output boards
SSR-RACK series solid state relay I/O module racks
A description of digital interfacing is in the Interface Electronics section.
IMPORTANT NOTE
The 82C55 digital I/O chip initializes all ports as inputs on power-
up and reset. A TTL input is a high impedance input. If you
connect another TTL input device to the 82C55 it could be turned
ON or OFF every time the 82C55 is reset.
Remember, the 82C55 is reset to the INPUT mode.
There are positions for pull-up and pull-down resistor packs on your PCI-DIO96
board. To implement these, please refer to section 7.1.
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