Measurement Computing USB-2416 - Manual (Page 13)

USB-2416 User's Guide Functional Details
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LEDs
When the USB-2416 is connected to a computer, in its normal idle state both LEDs are lit solid green.
Power LED
The Power LED is the top LED on the right side of the USB-2416 housing.
The Power LED blinks when you plug the power supply into the USB-2416, and continues to blink while the
device initializes the hardware. If it continues blinking for more than ½ second, then there is a problem with the
USB-2416 and you should cycle the power.
If an application issues a "blink LED" command, then the power LED blinks a few times.
Activity LED
The (USB) Activity LED is the bottom LED on the right side of the USB-2416 housing. It blinks rapidly when
both the USB cable and external power cables are plugged in. It continues blinking rapidly while the device is
connecting to the computer, and then turns solid.
Whenever the device receives a USB command, the Activity LED blinks off and then returns to solid green.
When an analog in scan is running, the Activity LED blinks continuously.
USB connector
The USB connector is on the right side of the USB-2416 provides communication.
External power connector
The USB-2416 require external power through this connector to provide sufficient power for the USB-2416.
Connect the PS-5V2AEPS power supply to the external power supply connector. This power supply provides
5 VDC, 2 A power to the USB-2416.
Screw terminal wiring
The USB-2416 has six groups of screw terminals—three on each side of the housing. Each group has
16 connections. Pin numbers are identified in Figure 4 and Figure 5.
Analog/TC input terminals
You can connect up to 32 single-ended analog input connections or up to 16 differential analog/TC input
connections to these screw terminal pins.
 CH0H and CH0L
 CH1H and CH1L
 CH2H and CH2L
 CH3H and CH3L
 CH4H and CH4L
 CH5H and CH5L
 CH6H and CH6L
 CH7H and CH7L  CH8H and CH8L
 CH9H and CH9L
 CH10H and CH10L
 CH11H and CH11L
 CH12H and CH12L
 CH13H and CH13L
 CH14H and CH14L
 CH15H and CH15L
You can select a unique input range or signal type for each channel. For example, one channel could be used for
volts and another for temperature.
When connecting differential voltage inputs to a "floating" voltage source, make sure there is a DC return path
from each voltage input to ground. You make this path by connecting a resistor from each input to a GND pin
(pins 18, 36, 39, 42, 44, 46, 66, 81, 84). A value of approximately 100 k
Ω can be used for most applications.
This does not apply to channels configured for thermocouple input, as they have their own internal reference.
Leave unused input channels either floating or tied to GND (pins 18, 36, 39, 42, 44, 46, 66, 81, 84).
Source impedances should be kept as small as possible to avoid settling time and accuracy errors.