Chapter 3
Connecting the UMI-7774/7772 to Drives and Other Devices
National Instruments UMI-7774/7772 User Manual
3-4
ni.com
Voltage Considerations for the UMI-7774/7772
Caution
Do
not
connect the UMI-7774/7772 isolated power to a source greater than 30 V.
Doing so may cause damage to UMI-7774/7772 components.
To cause current to flow through the input, the voltage applied to the
following types of inputs should be greater than 3.5 V and less than 30 V.
•
Fault inputs
•
Limit and home inputs
•
Global Stop inputs
•
Trigger inputs
•
General-purpose digital inputs
Also, the source must be able to provide at least 7.2 mA to turn on the
optical isolator
and result in an ON condition. When the applied voltage
is below 2 V, the input results in an OFF condition.
Optical isolation is a method for transmitting a signal from its source to
a measurement device without a physical connection by using an optical
coupling technique. Optical isolation can help break ground loops in the
system and reduce the effects of noise and voltage transients.
Power Requirements
The UMI-7774/7772 includes a 4-position power connector that provides
voltage and common for the main power supply as well as voltage and
common for the isolated output circuitry.
