Chapter 2
Hardware Overview
©
National Instruments Corporation
2-5
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
IN
+
Current
Limiter
NI 1426
IN
–
PNP (Sourcing)
Output Device
Sensor
Common