National Instruments NI PCI-8254R Isolated Inputs and Outputs

Chapter 2 Digital I/O

© National Instruments Corporation 2-3 NI PCI-8254R User Manual

Isolated Inputs and Outputs

The isolated inputs and outputs on the NI 8254R have a separate ground

reference from the main NI 8254R device supply, providing an easy means

to prevent ground loops that can introduce noise into a system. You can

apply signals up to 30 V to the isolated inputs. The voltage swing of the

isolated outputs is determined by the voltage you supply on the 2-position

isolated outputs power connector.

Note Viso is referred to as V, and Ciso is referred to as C on the 2-position isolated outputs

power connector on the NI 8254R.

Note The isolated outputs have current-limiting protection circuitry. If this circuitry is

tripped, you can re-enable the outputs by removing the fault and restarting your computer.

Watchdog Output 1TTL Output 0 3 4

General

Purpose Output 3TTL Output 5

TTL Output 6

TTL Output 7

19

21

22

21

23

24

* TTL Input 0 and TTL Input 1 can also function as trigger change detectors.

Table 2-1. NI 8254R TTL Inputs and Outputs (Continued)

Primary

Function

Input

or

Output Number

Available Signal Names

44-Pin

D-SUB on

NI 8255R

Device Pin

Number

37-Pin

Terminal

Block

Number

Contents

Main Page Important Information Warranty Copyright Trademarks Patents Compliance Compliance with FCC/Canada Radio Frequency Interference Regulations Determining FCC Class FCC/DOC Warnings Class A Conventions Contents Chapter 1 Introduction Chapter 2 Digital I/O Page Introduction Software Overview Vision Builder for Automated Inspection Vision Development Module IEEE 1394 and NI 8254R Functional Overview Start Conditions Acquisition Window Control Digital I/O RIO and LabVIEW FPGA TTL Inputs and Outputs Isolated Inputs and Outputs I/O for Normal Operation Trigger Inputs Timed Pulse Output Initiating a Timed Pulse Pulse Modes Pulse Delay Pulse Width Trigger Polarity Trigger Change Detectors Quadrature Encoder Product Selection Port Using ISO Input 5 as a Latch General-Purpose I/O General-Purpose Inputs General-Purpose Outputs I/O for Fault Conditions Shutdown Watchdog Timer Considerations When Connecting the Digital I/O Wiring an Isolated Input to a Sourcing Output Device Wiring an Isolated Output to an External Load Protecting Inductive Loads Transmission Line Effects Signal Connections The following diagram shows the connectors on the NI 8254R device. Connectors V C 2-Position Isolated Outputs Power Connector IEEE 1394a Connector General-Purpose Digital I/O Page Page Page Page Cabling IEEE 1394 Camera Cables I/O Terminal Block V C NI Vision I/O Terminal Block and Prototyping Accessory Power Requirements Isolated Outputs Power Connector Page A Technical Support and Professional Services Page Glossary F H I N P Q R T Page Index N P Q R S T W