Measurement Computing USB-PDISO8/40 - Manual (Page 14)

USB-PDISO8/40 User's Guide Functional Details
External power connectors
The USB-PDISO8/40 has two external power connectors labeled
POWER IN
and
POWER OUT
on the
enclosure. The
POWER IN
connector is labeled
PWR IN
on the board, and the
POWER OUT
connector is
labeled
PWR OUT
on the board.
To supply external power, connect the
POWER IN
connector to the supplied +9 V external power supply (CB-
PWR-9).
The
POWER OUT
connector lets you power additional daisy chained Measurement Computing USB products
from a single external power supply. The C-MAPWR-x cable is available from MCC to connect additional
Measurement Computing USB products.
USB LED
The
USB
LED indicates the communication status of the USB-PDISO8/40. This LED uses up to 5 mA of
current and cannot be disabled. explains the function of the USB LED. Table 3-1
Table 3-1. USB LED illumination
USB LED
illumination Indication
Steady green The USB-PDISO8/40 is connected to a computer or external USB hub.
Blinks continuously Initial communication is established between the USB-PDISO8/40 and the computer, or data is
being transferred.
PWR LED
The USB-PDISO8/40 incorporates an on-board voltage supervisory circuit that monitors the external 9 V power
supply. If the input voltage falls outside of the specified ranges the
PWR
LED shuts off (see ). Table 3-2
Table 3-2. PWR LED illumination
PWR LED
illumination Indication
Steady green +9 V external power is supplied to the USB-PDISO8/40.
Off Input power is not supplied, or a power fault has occurred. A power fault occurs when the input
power falls outside of the specified voltage range:
External power (+9 V): 6.5 V to 12.5 V
Direct current (dc) power connector and +9 V power supply
The USB-PDISO8/40 requires between 6.5 V and 12.5 V of external power. An external power connection is
required to activate the relays and to run tests in InstaCal.
The USB specification allows high power devices to draw up to 500 mA. When all eight relays are energized,
the collective current draw exceeds the maximum allowed for high power USB devices. Therefore, external
power is required.
Use the +9-volt (V) DC power supply cord shipped with the USB-PDISO8/40 to provide external power to this
connector.
3-2