©
National Instruments Corporation
15
NI UMI-7774/72 User Guide and Specifications
Caution
Do
not
connect the UMI-7774/72 isolated power to a source greater than 30 V. Doing so
may cause damage to UMI-7774/72 components.
V
iso
and C
iso
are redistributed to other connectors on the UMI-7774/72 as an output power source for
external devices. Refer to Figure 1 to locate the power input terminal block on the UMI-7774/72. Figure 13
shows the 4-position power connector. Table 1 shows the power connector terminal block pinout.
Table 1 includes descriptions of each of the terminals on the UMI-7774/72 power connector.
If you do not connect a separate power supply to the V
iso
and C
iso
terminals you must connect the V and
V
iso
terminal together and connect the C and C
iso
terminal together.
Note
When the drive enable output and digital output signals are in an ON state, they provide the
power connected on V
iso
and C
iso
. Use a power supply with a voltage that is compatible with the
inputs that the drive enable and digital outputs are connected to. V
iso
and C
iso
do
not
provide safety
isolation.
Connecting Power To the UMI-7774/72
The UMI-7774/72 includes a 4-position power connector that provides voltage and common for the
main power supply as well as voltage and common for the isolated output circuitry.
Figure 13.
UMI-7774/72 Power Input
Complete the following steps to wire power to the UMI-7774/72.
1.
Connect the positive lead of the 24 VDC power supply to the V terminal and the negative lead to
the C terminal on the UMI-7774/72.
2.
If you are using a separate power supply for optical isolation, connect the positive lead of the
5–30 VDC supply to the V
iso
terminal and the negative lead to the C
iso
terminal on the
UMI-7774/72.
3.
If you are not using the isolation feature on the UMI-7774/72, you must connect the V and V
iso
terminal together and connect the C and C
iso
terminal together.
Table 1.
Power Connector Terminals
Terminal
Description
V
Main power (24 V ±10%)
C
Common
V
iso
Isolated power (5 to 30 VDC)
C
iso
Isolated common
C
V
Vi
s
o
Ci
s
o
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