Relay control logic polarity, Relay power-on state, Connecting the external power supply – Measurement Computing USB-ERB24 User Manual
Page 13: Connecting the external power supply -3
USB-ERB24 User's Guide
Installing the USB-ERB24
Relay control logic polarity
Configure the
Invert/non-invert
switch (S1) to set the relay control logic polarity for each relay bank for invert
or non-invert. By default, this switch is shipped with all banks configured for non-inverted logic, as shown in
Figure 2-4. Relay logic switch S1
NON-INVERT
INVERT
S1
CL
CH
A
B
NON-INVERT
mode: when "0" is written or read back via the USB bus, the relays are not energized.
INVERT
mode: when "0" is written or read back via the USB bus, the relays are energized.
Switch settings for polarity can be read back via software through the USB bus. Switch settings for S1 do not
affect the power-on condition.
Relay power-on state
Configure the
Pull-up/pull-down
switch (S2) to set the state of each relay bank at power-up. By default, this
product is shipped with the switch for all banks configured for pull-down (relays inactive at power up), as
shown in Fi
. Switch settings can be read back via software through the USB bus.
Figure 2-5. Resistor pull-up/down switch S2
S2
PULL UP
PULL DOWN
CL
CH
A
B
PULL-UP
: the relays are put into an energized state at power-up, regardless of the state of switch S1
PULL-DOWN
: the relays are put into a non-energized state at power-up.
Connecting the external power supply
Power to the USB-ERB24 is provided with the 9 V, 3 A external power supply (CB-PWR-9V3A). You must
connect the external power supply before connecting the USB connector to the USB-ERB24.
To connect the power supply to your USB-ERB24, do the following:
1.
2.
Connect the external power cord to the power connector labeled
POWER IN
on the USB-ERB24 enclosure
(
PWR IN
on the board). Refer to Fi
for the location of this connector.
Plug the AC adapter into a power outlet.
The
PWR
LED illuminates green when 9 V power is supplied to the USB-ERB24. If the voltage supply is less
than 6.0 V or more than 12.5 V, the PWR LED does not light.
Do not connect external power to the POWER OUT connector
The power connector labeled
POWER OUT
on the enclosure (
PWR OUT
on the board) is used to provide power
to an additional MCC USB Series product. If you connect the external power supply to the
POWER OUT
connector, the USB-ERB24 does not receive power, and the
PWR
LED will not illuminate.
2-3