National Instruments Data Acquisition Device NI USB-621x - Manual (Page 33)

Chapter 3 Connector and LED Information
NI USB-621x User Manual 3-5 ni.com
PWR/ACT LED Indicator
The PWR/ACT LED indicator indicates device status. Table 3-2 shows the
behavior of the PWR/ACT LED.
Table 3-2. PWR/ACT LED Status
LED State Device Status
Not lit Device not powered or device error. Refer to ni.com/support if
device is powered.
On, not blinking Device error. Refer to ni.com/support .
Single-blink Operating normally. Connected to USB Hi-Speed port. Refer to the
NI USB-621x Specifications for more information.
Double-blink Connected to USB Full-Speed port. Device performance might be
affected. Refer to the NI USB-621x Specifications for more information.