National Instruments NI 9481 - Manual (Page 8)

NI 9481 Operating Instructions and Specifications 8 ni.com
Each electromechanical relay channel has two interchangeable
terminals, CHa and CHb.
Each channel has an LED that indicates the state of the channel.
When a channel LED is lit, the channel is on. When the LED is
dark, the channel is off. The LEDs are disabled when the chassis
is in sleep mode. Refer to the
Sleep Mode section for more
information about sleep mode.
When connecting a load to the NI 9481, connect the positive lead
of the load to either the CHa or the CHb terminal, and the ground
of the load to one of the leads of the power supply. Connect the
remaining CHa or CHb terminal to the other lead of the power
supply. Figure 3 shows a possible configuration.
Figure 3. Connecting a Load to the NI 9481
NI 9481
+
–
CHa
CHb
AC
or
Load