3.4.2 Connection to USB-powered Hub
In this example, two OM-DAQ-USB-2401s are connected by cable to individual ports of a single USB-powered hub. Since the hub receives all its power from the computer’s USB, the hub cannot supply adequate power to the DAQ units. Because of this aspect of insufficient power, each unit is connected to its own power adaptor.
USB
HUB
USB
Figure 3-4. Connection to USB-Powered Hub
NOTE:
The power adaptors used must be capable of supplying at least 500 mA and have a voltage rating of +7.5 to +12 Vdc.
3.4.3 Connections to Self-Powered and USB-powered Hubs
This example illustrates a system that makes use of four DAQ units and two different style USB hubs. Two DAQs are connected by cable to individual ports of a self-powered USB hub. In addition, the self-powered hub is connected to a downstream USB-powered hub, which is also connected to two DAQ units.
Notice that the DAQ units connected to the self-powered hub have no adaptors connected to them. This is because the hub receives external power (in addition to the PC supplied USB power), which is capable of supporting the downstream devices connected directly to it. In comparison, the three OM-DAQ-USB-2401s connected to the USB-powered hub each require their own power adaptor. As in example 3.4.2, the power adaptors used must be capable of supplying at least 500 mA and have a voltage rating of +7.5 to +12 Vdc.
