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# Features

■ PXI specifications Rev. 2.2 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
■ Switching capacity
- 2 A switching, 2 A carrying
- 220 V $_{DC}$ , 125 V $_{AC}$
Onboard I k-sample scan list for deterministic scanning
- Handshaking signals for external instruments synchronization
■ Design for safety-critical applications
Hardware emergency shutdown with programmable relay safety status
- Watchdog timer from 1 ms to 420 s with programmable relay safety status
■ Multiple modules synchronization through PXI trigger bus and star trigger
■ Fully software programmable

Operating Systems

\- Windows 7/10 x64/x86

Driver and SDK

\- VB/VC++

\- LabVIEW

# Introduction

ADLINK's PXI-7921 is a relay multiplexer which consists of 24 2-wire relays (DPDT, 2 Form C). As a multiplexer, the PXI-7921 provides 48x1 1-wire, 24x1 2-wire and 12x1 4-wire configurations. Users could choose one of the configurations by software. The PXI-7921 typically connects one instrument, such as a DMM, a digitizer or a signal source, with many points which need measurement or excitation.

The contact position of the relays can be changed either by direct software commands or by following the instructions previously stored in the onboard scan list. The scan list advances upon the trigger from external measurement devices, such as a DMM. The scan list could also advance when the scan-delay timer expires. In the PXI-7921, PXI trigger functions are supported and software programmable. Multiple modules can therefore be synchronized without additional field wiring.

Specifications

<table><tr><td>Source Wire</td><td>Multiplexer</td></tr><tr><td>1-wire</td><td>One 48x1</td></tr><tr><td>2-wire</td><td>One 24x1, Two 12x1, Four 6x1</td></tr><tr><td>4-wire</td><td>One 12x1</td></tr></table>

# Relay Characteristics

■ Number of channels: 24 (2-wire)
■ Relay type: DPDT (2 Form C), non-latching
Switching capacity

· Max. switching current: 2 A

· Max. switching voltage: 220 V $_{DC}$ , 125 V $_{AC}$

· Max. switching power: 60 W

· Max. carrying current: 2 A

■ Contact resistance: 100 mΩ max.
Relay set/reset time

· Operate time: 4 ms max.

\- Release time: 4 ms max.

Expected life
- Mechanical life: $10^{8}$ operations min.
- Electrical life: $5 \times 10^{5}$ operations min. (I A @ 30 VDC, resistive load)
■ Data transfer: programmed I/O

# Handshaking Signals

Programmable polarity
■ Logic level: 3.3 V/TTL (5 V tolerant)
■ TRG\_IN source: PXI trigger bus, PXI star trigger input
■ S\_ADV destination: PXI trigger bus

# Safety Functions

Emergency shutdown
· Logic level: 3.3 V/TTL (5 V tolerant)
· Active with logic low
Watchdog timer
- Base clock available: 10 MHz, fixed
- Counter width: 32-bit

# General Specifications

I/O Connector: 62-pin D-sub male
- Operating temperature: 0°C to 55°C
■ Storage temperature: $-20^{\circ}C$ to $70^{\circ}C$
■ Relative humidity: 5% to 85% non-condensing
■ Power requirements: (when all relays are ON)

<table><tr><td>Device</td><td>+5 V</td><td>+3.3 V</td></tr><tr><td>PXI-7921</td><td>IA</td><td>400 mA</td></tr></table>

# Certifications

EMC/EMI: CE, FCC Class A

# Ordering Information

# PXI-7921

24-CH 2-Wire Multiplexer Module

\* Failure rate indicates the lower limit of switching capacity of a relay contact at a reliability level of 60%

# Terminal Boards & Cables

# TB-6221-01

Multiplexer Switch Terminal Board with One 62-Pin D-Sub Female Connector

# ACL-10262

62-pin D-sub male/female cable, I M

(For more information about mating cables, please refer to P4-28.)

Pin Assignment
CNI

<table><tr><td></td><td>22. +5Vout</td><td></td></tr><tr><td>43. COM2+</td><td>23. CH8+</td><td>1. CH0+</td></tr><tr><td>44. COM2-</td><td>24. CH8-</td><td>2. CH0-</td></tr><tr><td>45. COM3+</td><td>25. CH9+</td><td>3. CH1+</td></tr><tr><td>46. COM3-</td><td>26. CH9-</td><td>4. CH1-</td></tr><tr><td>47. CH18+</td><td>27. CH10+</td><td>5. CH2+</td></tr><tr><td>48. CH18-</td><td>28. CH10-</td><td>6. CH2-</td></tr><tr><td>49. CH19+</td><td>29. CH11+</td><td>7. CH3+</td></tr><tr><td>50. CH19-</td><td>30. CH11-</td><td>8. CH3-</td></tr><tr><td>51. CH20+</td><td>31. CH12+</td><td>9. CH4+</td></tr><tr><td>52. CH20-</td><td>32. CH12-</td><td>10. CH4-</td></tr><tr><td>53. CH21+</td><td>33. CH13+</td><td>11. CH5+</td></tr><tr><td>54. CH21-</td><td>34. CH13-</td><td>12. CH5-</td></tr><tr><td>55. CH22+</td><td>35. CH14+</td><td>13. COM0+</td></tr><tr><td>56. CH22-</td><td>36. CH14-</td><td>14. COM0-</td></tr><tr><td>57. CH23+</td><td>37. CH15+</td><td>15. COM1+</td></tr><tr><td>58. CH23-</td><td>38. CH15-</td><td>16. COM1-</td></tr><tr><td>59. IWireloRef</td><td>39. CH16+</td><td>17. CH6+</td></tr><tr><td>60. TRG_IN</td><td>40. CH16-</td><td>18. CH6-</td></tr><tr><td>61. S_ADV</td><td>41. CH17+</td><td>19. CH7+</td></tr><tr><td>62. SHDNn</td><td>42. CH17-</td><td>20. CH7-</td></tr><tr><td colspan="2"></td><td>21. GND</td></tr></table>
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