Functional Description; Isolated Inputs; Extending The Input Range - Measurement Computing PCI-PDISO16 User Manual

Functional Description

Isolated inputs

The PCI-PDISO16 board has eight isolated input channels. A schematic of a single channel is shown in
4-1 . The signals are routed through a bridge rectifier so that the inputs are not polarity sensitive.
470 Ohm

Extending the input range

To extend the input range beyond the 5-28V specified, add an external resistor.
and the equations used to calculate resistor values for a given V
V
in
Digital I/O Techniques
For more information about digital I/O techniques, refer to the Guide to Signal Connections. This document is
available on our web site at www.mccdaq.com/signals/signals.pdf.
Isolated Input
Not Polarized
Figure 4-1. Isolated input channel - simplified schematic
R ext
R ext = 100 * (Vin - 28)
Pw = R ext / 10 000
Figure 4-2. Input voltage range extender resistor
+5V
100K
47K
Circuitry Sharing
PC Ground
.
in
1.6 K
Isolated Input
Not Polarized
4-1
Chapter 4
Figure
Filter Switch
0.1uF
Figure 4-2 shows the resistor