
Configuration and Installation
Chapter 2
SCXI-1160 User Manual
2-10
© National Instruments Corporation
Front Connector Signal Descriptions
Pin
Signal Name
Description
A1, A3, A5, A7,
NO <15..0>
Normally Open Contact – These are the
A9, A11, A13,
normally open contacts of the relays
A15, A17, A19,
15 through 0.
A21, A23, A25,
A27, A29, A31
B2, B4, B6, B8,
COM <15..0>
Common Contact – These are the common
B10, B12, B14,
contacts of the relays 15 through 0.
B16, B18, B20,
B22, B24, B26,
B28, B30, B32
C1, C3, C5, C7,
NC <15..0>
Normally Closed Contact – These are the
C9, C11, C13,
normally closed contacts of the relays
C15, C17, C19,
15 through 0.
C21, C23, C25,
C27, C29, C31
All contacts have a working common mode voltage of 250 VAC or VDC. The contact-to-
contact breakdown voltage is 750 Vrms. The contact-to-coil breakdown voltage is 1,500 Vrms.
Please refer to the module specifications listed in Appendix A for further details before
connecting the signals to the relay contacts.
Contact Protection for Inductive Load Connections
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.
It is best to limit these flyback voltages at your inductive load by installing a flyback diode for
DC loads or an MOV for AC loads. Refer to the section, 3. Contact Protection, in Appendix F,
Aromat Relay Technical Data , for further details.
In addition, the module contains pads on which you can place an arc suppressor protection circuit
to limit the voltage spike generated during the switching of inductive loads. These pads are
located between the COM position and the NO position and between the COM position and the
NC position of the relays.