Measurement Computing CIO-DISO48 - Manual (Page 13)

12
Chapter 3
Functional Details
Isolated inputs
The CIO-DISO48 has 48 isolated input channels. A schematic of a single channel is shown in Figure 6.
Figure 6. Isolated input schematic – simplified
AC or DC input signals are applied to a bridge rectifier so that the inputs are not polarity sensitive. On AC
inputs, the bridge output is a "pulsating" DC voltage. Closing the filter switch smoothes this pulsating voltage to
steady DC.
Extending the input range
To extend the input range beyond the 5-28 V specified, add an external resistor. Figure 7 shows the resistor and
the equations used to calculate resistor values for a given Vin.
Figure 7. Input range-extending resistor
For more information on digital signal connections
For more information on digital signal connections and digital I/O techniques, refer to the Guide to Signal
Connections. This document is available on our web site at available on our web site at
www.mccdaq.com/signals/signals.pdf ).