National Instruments Interface Device NI PCI-1426 - Manual (Page 17)

Chapter 2 Hardware Overview
NI PCI-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