Contec AIO-120802LN-USB, User Manual

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3. Connection and Installation
AIO-121602LN-USB, AIO-120802LN-USB
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Analog Input Signal Connection
The procedure for connecting analog signals depends on whether the analog input signals are
single-ended or differential. The sections below describe how to connect the signals using flat cable and
shielded cable.
Single-ended Input
The following figure shows an example of flat cable connection.
Connect separate signal and ground wires for each analog input channel on interface connector.
Figure 3.16. Single-ended Input Connection (Flat Cable)
The following figure shows an example of shield cable connection. Use shielded cable if the distance
between the signal source and unit is long or if you want to provide better protection from noise. For
each analog input channel on interface connector, connect the core wire to the signal line and connect
the shielding to ground.
Figure 3.17. Single-ended Input Connection (Shielded Cable)
- If the signal source contains over 500 kHz signals, the signal may affect the cross-talk noise
between channels.
- If the unit and the signal source receive noise or the distance between the unit and the signal source
is too long, data may not be input properly.
- An input analog signal should not exceed the maximum input voltage (relate to the product analog
ground). If it exceeds the maximum voltage, the unit may be damaged.
- Connect all the unused analog input channels to analog ground.
- In the channel switching, the multiplexer does the electrical charge and discharge on the internal
capacitor according to the signal voltage. Therefore, the voltage from the previous switching state
may go into the next channel. It might cause the error of the signal source action. If this occurs,
insert a high-speed amplifier as a buffer between the signal source and the analog input pin to
reduce the fluctuation.
- An input pin may fail to obtain input data normally when the signal source connected to the pin has
high impedance. If this is the case, change the signal source to one with lower output impedance or
insert a high-speed amplifier buffer between the signal source and the analog input pin to reduce the
effect.
CAUTION