Chapter 3
Digital I/O Functionality
NI CVS-1450 Series User Manual
3-14
ni.com
Protecting Inductive Loads
When an inductive load, such as a relay or solenoid, is connected to an
output, a large counter-electromotive force may occur at switching time
due to energy stored in the inductive load. This flyback voltage can damage
the outputs and the power supply.
To limit flyback voltages at the inductive load, install a flyback diode across
the load. Mount the flyback diode as close to the load as possible. Use
this protection method if you connect any of the isolated outputs on the
NI CVS-1450 device to an inductive load.
Figure 3-7 shows an example of using an external flyback diode to protect
inductive loads.
Figure 3-7.
Example of Using an External Flyback Diode for Inductive Loads
Digital
Output
V
iso
C
iso
V
cc
NI CVS-1450 device
External
Fly
b
ack
Diode for
Inductive Loads
Load
