NI 9753 User Manual
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© National Instruments
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3
Hardware
The NI 9753 has eight channels of RS485/422 compatible differential digital inputs or outputs
in a NI CompactRIO module form factor and provides a 5 V sensor power output and ground.
NI recommends using the NI 9923 Connector Kit for connections to the NI 9753. The NI 9923
provides proper strain relief for NI 9753 connections. Visit
ni.com/info
and enter Info Code
DIFFIO
for more information on parts and accessories for the NI 9753.
Powering the Module
The NI 9753 requires power from two different sources, the CompactRIO backplane male high
density D-SUB 15-pin (HD15) connector and the external DB-37 connector.
The HD15 connector mates with the module’s female HD15 connector. It provides a regulated
5 V and ground to various digital logic functions within the NI 9753. It is active whenever the
CompactRIO or R Series Expansion Chassis is properly powered. The NI 9753 should be
powered at the HD15 connector by plugging it into a CompactRIO or R Series Expansion
Chassis. The module’s HD15 connector should not be connected to any other device.
The other power connection is at the external DB-37 connector labeled BATT (19) and GND
(18). Typical power sources will be from automotive 12 V or 24 V battery systems. The NI 9753
can accept power from a range of 6 V to 32 V. The maximum power to the NI 9753 is limited to
5 W. When the 5 V supply output is not being utilized, the NI 9753 requires up to 2 W from the
external supply, depending on the number of channels operated as outputs and on their switching
frequency. The external 5 V supply output can be used for the remainder of the 5 W power limit.
If the external 5 V supply output is shorted or overloaded, then the voltage output level will be
reduced in order to limit the total power to 5 W. This will cause the I/O transceivers to shutdown.
The NI 9753 requires both external power and power from the CompactRIO backplane. The
NI 9753 directs the high current path through the BATT and GND terminals on the front of the
module and not through the HD15 backplane connector.
Note
The NI 9753 will not be recognized by software without both power supplies
active.
Note
The external battery supply is not required in order for the NI 9753 to be
recognized by LabVIEW FPGA software. The RS485/422 channel transceivers will
not be active without the external battery supply.
