scxi1162.pdf

SCXI 32-Channel Optically Isolated

Digital Input Modules

SCXI-1162

SCXI-1162HV

32 digital inputs

8 banks of 4 lines

300 V rms isolation per bank

TTL and CMOS

32 digital inputs

8 banks of 4 lines

300 V rms isolation per bank

TTL, CMOS, 240 VAC/VDC

Driver Software

NI-DAQ Software

Windows 2000/NT/Me/9x

Mac OS

Application Software

LabVIEW

Measurement Studio

Lookout

monitor TTL level inputs as well as sense the

presence of high-voltage AC and DC signals.

For example, you can use an SCXI-1162HV

to sense the on/off state of power circuits,

proximity switches, pushbutton switches,

thermostats, or relays. The SCXI-1162

interfaces directly to ﬁeld digital logic input

signals that should be isolated from the

host computer.

Signal Compatibility

EXPRESS

CODES

Module

TTL/CMOS

240 VAC/VDC

SCXI-1162

–

SCXI-1162HV

For information or to

buy products online,

visit ni.com/catalog

and enter:

Table 1. SCXI Module Compatibility

Overview

NI offers two optically-isolated digital input modules for SCXI, the

SCXI-1162 and the SCXI-1162HV. The SCXI-1162 has 32 channels of

optically-isolated digital inputs, arranged into eight isolated banks of

four input lines each. The SCXI-1162 interfaces to field digital logic

signals, such as TTL and CMOS, where high common-mode voltages

may be present. The SCXI-1162HV senses the presence of a wide

range of AC or DC signals, from digital logic level signals up to 240

VAC/VDC signals. The optical isolation of the SCXI-1162 and

SCXI-1162HV eliminates ground-loop problems and isolates the host

computer from damaging voltages.

The SCXI-1162 and SCXI-1162HV are programmed serially over the

SCXIbus. You can therefore easily integrate SCXI-1162 and SCXI-1162HV

modules into existing SCXI systems without additional DAQ devices or

cabling. The modules can also operate in parallel mode when cabled

directly to a DIO device.

scxi1162

scxi1162hv

Description

Figure 1 is a block diagram of the SCXI-1162 and SCXI-1162HV. The

major functions and operation of the modules are described in the

following paragraphs.

Vcc (SCXI-1162)

Optically

Isolated

Inputs

Parallel Data

COM (SCXI-1162HV)

Data

Serial Data

8 Banks of 4 Digital

Channels

Vcc (SCXI-1162)

Applications

You can use an SCXI system equipped with the SCXI-1162 or

SCXI-1162HV in a variety of industrial and laboratory applications. The

SCXI-1162 and SCXI-1162HV safely isolate the computer from the large

common-mode voltages, ground loops, and voltage spikes that often

occur in industrial and research environments. The SCXI-1162HV can

Optically

Isolated

Inputs

SCXI

Interface

Serial Data

COM (SCXI-1162HV)

Figure 1. SCXI-1162 and SCXI-1162HV Block Diagram

National Instruments

Tel: (512) 794-0100 • Fax: (512) 683-9300 • info@ni.com • ni.com

525

SCXI 32-Channel Optically Isolated

Digital Input Modules

This transfer rate was determined using a 500 MHz Pentium III

computer. The data register also has a 32-bit parallel interface to the

rear signal connector (for parallel operation with a plug-in DIO device).

Input Type

S C XI-1162HV

SCXI-1162

Switch/Pushbutton

Modes of Operation

Multiplexer

In serial mode, a single DAQ device reads 32-bit digital patterns from the

data register of one or more SCXI modules via the SCXIbus using a serial

data protocol. This serial-mode operation uses a maximum of ﬁve digital

I/O lines of the DAQ device. With serial-mode operation, you can control

several SCXI modules in one or more chassis using a single DAQ device.

NPN, sinking

(open-collector)

PNP, sourcing

(open-emitter)

Parallel

You can also operate the SCXI-1162 and SCXI-1162HV in parallel

mode, connecting each module directly to a digital I/O DAQ device –

6503 (DIO-24), 6533 (DIO-32HS), and 6508 (DIO-96). In this

conﬁguration, each input channel of the SCXI-1162 or SCXI-1162HV

module connects directly to a corresponding digital input line of the

digital I/O device.

Figure 2. Input Wiring Diagrams for SCXI-1162 and SCXI-1162HV

Optically Isolated Digital Inputs

The 32 channels of the SCXI-1162 and SCXI-1162HV are organized

into eight banks of four inputs each. Each bank is optically isolated

to 300 V rms from each other and from the SCXI chassis earth ground.

The SCXI-1162 accepts many types of digital signals, including

TTL, CMOS, and voltage references from 5 to 10 V (Figure 2).

A 360 Ω resistor in series

with the optoisolator

limits the current,

as diagrammed in

Figure 3. Each bank of

four input lines shares

one +5 to +10 V reference

voltage, V cc , supplied by

the user. Each input of

the SCXI-1162HV consists

of current-limiting circuitry

in series with a bidirec-

tional optoisolator, as

diagrammed in Figure 4.

Each bank of four inputs share a COM pin, to which you must connect

a ground reference. A positive or negative DC input signal with a

magnitude greater than 2 V, up to 240 V, turns on the optocoupler

circuit and register as a logic high. When sensing the presence of AC

signals, a 50 or 60 Hz sinusoidal signal with a magnitude of at least

10 VAC registers a constant logic high. A 1 kHz sinusoidal signal registers

a constant logic high when its magnitude exceeds 2 VAC. The

SCXI-1162HV returns a constant logic low as long as the peak

magnitude of the signal does not exceed ±1 V.

Signal Connection

Field digital signals connect to screw terminals located in the

SCXI-1326 terminal block, which plugs directly onto the front of the

SCXI module, or the TBX-1326, a DIN-rail mountable terminal block

that you connect to the SCXI-1162 or SCXI-1162HV using the

SH48-48-B shielded cable (Table 2).

V s

V CC

TTL Output to

SCXI-1162

Data Register

CHAN(X)

360

Figure 3. Digital Input

Diagram for SCXI-1162

Terminal Block

Type

Cabling

Page

SCXI-1326

Screw Terminals

–

539

Current

Limiter

CHAN(X)

(777687-26)

Front-mounting

TTL Output to

SCXI-1162HV

Data Register

Smoothing

Filter

COM

TBX-1326

Screw terminals

SH48-48-B

542

Figure 4. Digital Input

Diagram for SCXI-1162HV

(777207-26)

DIN-rail mount

Table 2. Terminal Block Options for SCXI-1162 and SCXI-1162HV

See page 470 to conﬁgure your complete SCXI system.

Ordering Information

SCXI-1162 ..........................................................776572-62

SCXI-1162HV ...................................................776572-62H

Extended warranty and

value added services ...........................................page 880

Data Register

The logical states of the 32 digital input channels are placed into the

32-bit data register. If the module is operating in serial mode, the 32-bit

data register value is read through the SCXIbus. You can access the data

526

National Instruments

Tel: (512) 794-0100 • Fax: (512) 683-9300 • info@ni.com • ni.com

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