Measurement Computing USB-ERB24 - Manual (Page 15)

Chapter 3
Functional Details
Internal components
The USB-ERB24 has the following internal components, as shown in Figure 3-1.
ƒ Two (2) USB connectors
ƒ Two (2) external power connectors
ƒ USB LED
ƒ PWR LED
ƒ Invert/non-invert switch (S1) — sets the relay control logic polarity
ƒ Pull-up/down switch (S2) — sets the relay power-on state
ƒ Screw terminals
Invert/non-invert
switch (S1)
PWR LED
USB LED
USB IN
POWER
OUT
POWER IN
USB
OUT
Pull-up/pull-down
switch (S2)
Screw terminals
Figure 3-1. USB-ERB24 components
USB in connector
The USB out connector is labeled USB IN on the board and enclosure.
The USB IN connector is a USB 2.0 full-speed input connector that you connect to the USB port on your
computer (or USB hub connected to your computer). This connector supports USB 1.1, USB 2.0 devices.
USB out connector
The USB out connector is labeled USB OUT on the board and enclosure.
The USB OUT connector is a downstream hub output port intended for use with other MCC USB Series
products only. The USB hub is self-powered, and can provide 100 mA maximum current at 5 V.
For information on daisy chaining to other MCC USB Series products, refer to Daisy chaining additional
modules to the USB-ERB08 on page 3-3.
External power connectors
The USB-ERB24 has two external power connectors labeled POWER IN and POWER OUT on the enclosure.
The POWER IN connector is labeled PWR IN and P19 on the board, and the POWER OUT connector is labeled
PWR OUT and P20 on the board.
Connect the POWER IN connector to the supplied +9 V external power supply. External power is required to
operate the USB-ERB24. The POWER OUT connector lets you power additional daisy chained MCC USB
Series products from a single external power supply. Depending on your load requirements, daisy chained
products may require a separate power supply. Refer to "
Power limitations using multiple USB-ERB24
devices " on page 3-4 for more information.
3-1