Measurement Computing CIO-DUAL-AC5 - Manual (Page 7)

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Chapter 1
Introducing the CIO-DUAL-AC5
Overview: CIO-DUAL-AC5 features
The CIO-DUAL-AC5 is a 48-bit digital I/O board. The 48-bits of digital I/O are organized into two 24-bit
groups based on an 82C55 mode 0 emulation (no strobed I/O or bi-directional I/O bits). Each 24-bit group is
divided into three eight-bit ports — Port A, Port B, and Port C. PORTC can be split into two four-bit nibbles —
Port C-HI and Port C-LO. Each port can be individually programmed as input or output.
The CIO-DUAL-AC5 has two 50-pin header connectors which are compatible with the pin out of OPTO-22
and GORDOS solid state relay racks. If you are using OPTO or GORDOS form factor solid state relay racks,
you can connect the CIO-DUAL-AC5 directly to the relay racks through 50-pin cables, such as the C50FE-x.
All inputs and outputs are TTL compatible. The digital output drivers are 74S244 chips that can sink 64 mA
and source 15 mA. The input buffers are 74LS373 chips and have standard high input impedance of the 74LS
series devices.
On power up and reset, all I/O bits are set to input mode. If you are using the board to control items that must
be OFF on reset, install pull-down resistors. Each board is equipped with open locations where you can install
SIP resistor networks for either pull-up or pull-down.
Software features
For information on the features of InstaCal and the other software included with your CIO-DUAL-AC5, refer
to the Quick Start Guide that shipped with your device.