©
National Instruments Corporation
B-1
B
Customizing Your Card
This appendix describes options for customizing your NI 2565 card.
Flyback Voltage Protection
When inductive loads are connected to the relays, a large counter
electromotive force may occur at relay switching time due to the energy
stored in the inductive load. These flyback voltages can severely damage
the relay contacts and greatly shorten the life of the relay.
You can limit flyback voltages at your inductive load by installing a flyback
diode for DC loads or a varistor for AC loads. The NI 2565 module has
solder connections for a diode or varistor. With this diode/varistor installed,
you can limit flyback voltages when switching inductive loads.
Caution
Before installing the diode or varistor in your module, ensure that no signals are
connected to your module front connector.
Before installing your module in the PXI chassis, install the diode/varistor
by performing the following steps. Refer to Figure B-1.
!