ADLINK USB-2401 - Manual (Page 32)

22 Getting Started
If the USB-2401 module cannot be detected, the power provided
by the USB port may be insufficient. The USB-2401 module is
exclusively powered by the USB port and requires 400 mA @ 5 V.
2.2 Device ID
A rotary control on the rear of the module (as shown) controls
device ID setting and can be set from 1 to 8. The device ID allows
dedicated control of the USB-2401 module irrespective of the con-
nected USB port. When more than one USB module of the same
type is connected, each must be set to a different ID to avoid con-
flicts and errors in operation.
Figure 2-2: Device ID Selection Control