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National Instruments PXI-8421/8 Eight-port RS-485/RS-422 serial interface module

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National Instruments · PXI

PXI-8421/8

The National Instruments PXI-8421/8 adds eight RS-485/RS-422 serial ports to a PXI system. Adapter cabling converts its 68-pin connector to eight DB-9 connections.

ManufacturerNational Instruments

ModelPXI-8421/8

Product TypeEight-port RS-485/RS-422 serial interface module

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Serial ports8

Serial standardsRS-485 and RS-422

IsolationNon-isolated

Module connector68-pin SCSI-type

Driver limitationPXI-8421 support was removed in NI-Serial 17.0

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Overview

Product overview

Key product information and technical features.

This eight-port PXI serial board provides communication with RS-485 and RS-422 devices. Its 16550-compatible UART architecture supports standard PC COM-port operation, while FIFO buffering reduces susceptibility to interrupt latency.

The PXI-8421 supports two-wire and four-wire devices with four hardware transceiver-control modes. Plan the adapter cabling and software environment before integration: NI-Serial 17.0 removed support for this interface family.

Eight serial ports through a single module connector.
Two-wire and four-wire RS-485 device support.
Four hardware transceiver-control modes.
FIFO buffering and standard PC COM-port compatibility.

Verified specifications

Technical data

Verified product specifications.

Port count	8 ports
Serial standards	RS-485/RS-422
Isolation	Non-isolated
I/O connector	68-pin SCSI-type connector
Dimensions	100 × 160 mm
Typical current at +5 VDC	1.1 A
Maximum current at +5 VDC	2.0 A

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National Instruments

Manufacturer

PXI

Hardware platform

PXI-8421/8

Eight-port RS-485/RS-422 interface

Software

NI-Serial 17.0 removed PXI-8421 support.

Confirm legacy driver support and the required adapter cabling before integration.

Manuals & software

Technical resources

Manuals, software and technical resources for this model.

NI Serial Legacy Hardware Specifications and Features GuideSpecifications And Features Guide · docs-be.ni.com

Getting Started with Your PXI Serial Hardware and Software for Windows NTArchived Installation And Operating Manual · docs-be.ni.com

NI-Serial 17.0 for Windows ReadmeDriver Support Notice · ni.com

PXI Serial Wiring and Transceiver-Control InstructionsTechnical resource

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FAQ

Product-specific questions

Product-specific answers based on available technical information.

Does the PXI-8421/8 support RS-422 as well as RS-485?

Yes. NI documents the PXI-8421 family for both protocols.

Are eight DB-9 connectors mounted on the module?

No. Adapter cabling converts the module's 68-pin connector to eight DB-9 connectors. Cable inclusion with this catalog item is not established.

Does NI-Serial 17.0 support this module?

No. NI explicitly removed PXI-8421 support in NI-Serial 17.0. Verify an earlier driver against the intended operating system.

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