User's Manual

Chapter 2 Hardware Overview

Note If not configured as single-ended I/O lines, triggers have input only capability.

Wiring an Isolated Input to Output Devices

You can wire an isolated input to both sourcing and sinking output devices.

Refer to Figures 2-3 and 2-4 for wiring examples by output type. Refer to

Getting Started with the NI PCI-1426 for information about switching

thresholds and current requirements.

Caution Do not apply a voltage greater than 30 VDC to the isolated inputs. Voltage greater

than 30 VDC may damage the NI 1426.

Note Isolated inputs are compatible with 5 V logic if the external circuit meets the voltage

and current requirements listed in Getting Started with the NI PCI-1426.

Figure 2-3. Example of Connecting an Isolated Input to a Sourcing Output Device

Table 2-1. Trigger Configuration Options for the NI 1426

Trigger Number

Single-ended

Input/Output

Alternative

Input Only

0 TTL_TRIG(0) ISO_IN(0)

1 TTL_TRIG(1) ISO_IN(1)

2 TTL_TRIG(2) RS422_IN(0)

3 TTL_TRIG(3) RS422_IN(1)

Vcc

Sensor

Power

Current

Limiter

NI 1426

–

PNP (Sourcing)

Output Device

Sensor

Common