Protecting Against Inductive Loads; Connecting To Serial Devices - National Instruments NI 17 Series User Manual

Figure 2-4. Connecting an Isolated Output to a Sinking External Load
NI 17xx

Protecting Against 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 to an inductive load.

Connecting to Serial Devices

Use the RS232_RXD and RS232_TXD signals on the POWER-I/O connector for serial
communication. Connect the RS232_RXD signal on the NI Smart Camera to the Tx signal on
your serial device. Connect the RS232_TXD signal on the smart camera to the Rx signal on your
serial device. Connect COM on the smart camera to the ground of your serial device.
When the CONSOLE DIP switch is in the OFF position, you can use the NI-Serial driver for
serial communication. You must install the NI-Serial software on the smart camera; it is not
installed by default. Refer to the Serial Hardware and Software Help for information about
installing the NI-Serial software on LabVIEW Real-Time targets, such as the smart camera. To
open this document, navigate to Start»All Programs» National Instruments»NI-Serial»
NI-Serial Help.
NI 17xx Smart Camera User Manual
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Power
IsoOut+
IsoOut–
Sinking
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Common