User`s manual

Introduction • 1

Introduction

ADLINK PXI-7921 is a relay multiplexer module which consists of 24 2-wire

relays (DPDT, 2 Form C). PXI-7921 provides 48x1 1-wire and 24x1 2-wire and

12x1 4-wire configurations and typically connects one instrument, such as a

DMM, a digitizer or a signal source, with many points which need measurement

or excitation.

Relays of PXI-7921 can be updated by either direct-update mode or auto-scan

mode. The latter mode supports scanlist of 1k-sample for deterministic

scanning.

PXI trigger functions are fully supported and software programmable. The

multiple switch modules can be synchronized and triggered without additional

field wiring.

For safety critical applications, PXI-7921 module can switch to the preset state

by either asserting emergency shutdown manually, or watchdog timer overflow

event.

1.1 Features

• PXI specifications Rev. 2.0 compliant

• 3U Eurocard form factor, CompactPCI compliant (PICMG 2.0 R3.0)

• PICMG 2.1 R2.0 CompactPCI Hot-Swap

specifications compliant

• 24-CH DPDT (2 Form C) non-latching relays

• Contact rating

• 2A switching, 2A carrying

• 220V

, 125V

• 125 operations per second

• 1k-sample scanlist for deterministic scanning

• Provides handshaking signals to trigger external instruments

• Programmable emergency shutdown function and Watchdog timer for

safety critical applications

• Three auxiliary 3.3V/TTL digital inputs/outputs with 5V tolerance

• Supports PXI backplane triggers to synchronize multiple modules

• Fully software programmable