Chapter 2 Hardware Overview
NIPCI-1426 User Manual 2-6 ni.com

Figure 2-4. Example of Connecting an Isolated Input to a Sinking Output Device

Connecting to a Quadrature Encoder

The NI 1426 accepts differential (RS-422) line driver inputs. Shielded

encoder cables are recommended for all applications. Unshielded cables

are more susceptible to noise and can corrupt the encoder signals. Refer to

Figure 2-5 for an example of connecting differential line drivers.

Figure 2-5. Example of Connecting Differential Line Drivers

Vcc
Sensor
Power
IN+Current
Limiter
NI 1426
IN–
NPN (Sinking)
Output Device
Sensor
Common
26LS32
+
–
Phase A+
Phase A–Phase A–
Phase A 7
8
Twisted
Pair
26LS32
+
–
Phase B+
Phase B–Phase B–
Phase B 14
15
Twisted
Pair
Encoder NI 1426