© National Instruments
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3-13
Connecting to Differential I/O
The NI CVS-1459RT accepts differential (RS-422) line driver inputs. Each of the 2 differential
I/O can be configured as an output. Use shielded cables for all applications. Unshielded cables
are more susceptible to noise and can corrupt signals. Figure 3-11 shows the differential
input/quadrature encoder input circuit. Figure 3-12 and Figure 3-13 show differential and
single-ended line driver connections.
Figure 3-11.
Quadrature Encoder/RS-422 Input/Output Circuit
+
–
Diff I/O 0–
Diff I/O 0+
Diff I/O 1–
Diff I/O 1+
+
3
.
3
V
+
–
10 k
Ω
10 k
Ω
10 k
Ω
10 k
Ω
EN
EN
7.5 k
Ω
7.5 k
Ω
7.5 k
Ω
7.5 k
Ω
