Signal Connections
Chapter 3
SCXI-1162HV User Manual
3-4
© National Instruments Corporation
Front Connector Signal Descriptions
Pin
Signal
Description
B30, A30, B29,
A29, C29
In <0..3>, GND
Bank 0 input channels and ground reference.
B26, A26, B25,
A25, C25
In <4..7>, GND
Bank 1 input channels and ground reference.
B22, A22, B21,
A21, C21
In <8..11>, GND
Bank 2 input channels and ground reference.
B18, A18, B17,
A17, C17
In <12..15>, GND
Bank 3 input channels and ground reference.
A13, B13, A14,
B14, C14
In <16..19>, GND
Bank 4 input channels and ground reference.
A9, B9, A10,
B10, C10
In <20..23>, GND
Bank 5 input channels and ground reference.
A5, B5, A6,
B6, C6
In <24..27>, GND
Bank 6 input channels and ground reference.
A1, B1, A2,
B2, C2
In <28..32>, GND
Bank 7 input channels and ground reference.
C1, C5, C9,
C13, C18,
C22, C26, C30
NC (No Connect)
Unused pins.
Input Channels
The optically isolated inputs of the SCXI-1162HV consist of bidirectional light-emitting diodes
and current-limiting circuitry. The SCXI-1162HV has eight banks of four of these optically
isolated inputs. Each bank of inputs has a separate connection for the ground reference (GND)
for that bank. The four inputs of each bank are referenced to the GND of that bank, so for any
bank of inputs to work, a GND must be connected to that bank. When a voltage is applied
between an input and its ground, signal current flows through the input and the diode emits light
that is sensed by a photosensitive circuit. When this circuit senses the light, it returns a logic-
high digital signal.
Sensing DC Voltages
When a positive or negative DC voltage with a magnitude of at least 2 V is referenced to the
GND of a bank and is applied to an input of that bank, the SCXI-1162HV registers a logic high
for that input. Current-limiting circuitry limits the input current to 1.5 mA for input voltages up
to 240 VDC referenced to the GND signal. If there is no such voltage, the SCXI-1162HV will
register a logic low for that input. Thus, you can use the SCXI-1162HV to sense the presence of
a wide range of DC signals; from digital logic levels to DC power supply levels up to 240 V.
There is a delay of approximately 1 ms between the time a voltage is removed and the time the
SCXI-1162HV recognizes this change.