Cogent SST-DHP Driver for SST Data Highway Plus Cards : Version 1.5
	Chapter 1. Introduction

Chapter 1. Introduction

Table of Contents

1.1. Features and Specifications
1.2. System Requirements
1.3. Applicable Reference Documents

1.1. Features and Specifications

This device driver has been implemented as an OS task named sdadmin in QNX 4, QNX 6, and Linux. It receives requests from any task and performs the required Data Highway or Data Highway Plus access. (In QNX 4, the requests can come from any machine on the network.) The task can then be blocked waiting for completion or allowed to execute in parallel as the SST interface card performs the access. The following features have been implemented to maintain high performance in demanding applications:

Product Features

All communication with the SST card is through shared RAM.
Driver can queue 250 messages.
Only one interrupt is generated per message.
Multiple processes can use the same card and the same destination PLC at the same time; response routing and transaction number generation are managed by the administrator.

Specifications

Uses SST's ISA, PCI and PC/104 interface cards for Allen-Bradley.
Multiple interface cards can be configured in one computer.
Only one 32 Kbyte shared memory segment is required for all installed cards.
Address of shared RAM is software configurable.
Includes modules for both Data Highway and Data Highway Plus.
Simple installation and configuration.
Available for QNX version 4.23A and later, QNX 6 version 6.1.0 and later, and Linux version 2.4 and later.

It is assumed that the reader is familiar with Data Highway, Data Highway Plus, the C programming language and the intricacies of programming for the QNX or Linux operating systems, as applicable.


Cogent SST-DHP Driver for SST Data Highway Plus Cards		1.2. System Requirements