DIO24, User Manual
1. Introduction
1.1. Purpose
The purpose of this document is to briefly describe the DIO24 I/O board, its features, its use and its hardware
interface.
1.2. Plug and Play
The DIO24 is Plug and Play compatible. If the host is also Plug and Play compatible then the BIOS will recognize
and configure the DIO24 accordingly.
1.3. System Resources
Through Plug and Play initialization, the DIO24 is given three system resources. This includes a 256-byte block of
memory space for the PLX PCI9080 feature set registers, plus an identical block for the same registers that is
mapped to I/O port space. It also includes a 5
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2-byte block of memory for the GSC specific DIO24 registers. This
board requires neither a DMA channel nor an interrupt request line.
1.4. Hardware Overview
The DIO24 is a simple 25-bit discrete I/O interface board. The host side connection is PCI based and the external
I/O interface is variable (see below). The external interface includes 24 pins that can be arbitrarily programmed as
either input or output and one pin that is input only. The 24 programmable pins are divided into three groups of eight
pins each; Port A, Port B and Port C. Ports A and B are each programmable as all inputs or all outputs. The Port C
pins are individually programmable.
Figure 1
DIO24 simple block diagram.
PCI
Interface
PLX
PCI9080
DIO24
Internal
Logic
Transcievers
Cable
Interface
Port A (8 bits)
Port B (8 bits)
Port C (8 bits)
Dedicated
Input (1 bit) or
clock output
1.4.1. HOST Interface
The PCI interface on the DIO24 is implemented using the PCI9080 from PLX Technology. The PCI interface is
compliant with the 5V, 33 MHz PCI Specification 2.1. Although the PCI9080 supports DMA data transfers, DMA is
not supported on this product.
1.4.2. External I/O Interface
1.4.2.1. RS485/422 Interface
This interface provides for synchronous bus clock speeds up to 26MHz (104 Mbytes per sec). This is the standard
interface option.
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General Standards Corporation, Phone: (256) 880-8787
