ADLINK Technology NuDAQ 723 Series, User Manual, Page: 24 / 36

Registers & Operation Theorem
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On PCI-7234 and cPCI-7230, the VDD pin is used as “fly-wheel” diode,
which can protect the driver if the loading is inductance loading such as
relay, motor or solenoid. If the loading is resistance loading such as resistor
or LED, the connection to fly-wheel diode is not necessary.
Therefore, the first step for connecting the output with external device is to
distinguish the type of loading. For example, if the loading is LED or
resistor, you can use the following wiring diagram.
The VDD is opened on PCI-7234 and cPCI-7230.
+
- DD
V
Resistive
Loading
5~35V
-
EOGND
V
DD
If the loading is a inductance loading such as relay, you can use the
following wiring diagram. The VDD must connect to the external power to
form a fly-wheel current loop.
+
- DD
V
Inductance
Loading
5~35V
-
EOGND
V
DD
3.7 Change of State Detection
3.7.1 What is COS?
The COS (Change of State) means when the input state (logic level) is
changed from low to high or from high to low. The COS detection circuit is
used to detect the edge of level change. In the PCI-7233 card, the COS
detection circuit is applied to all the 32 channels input channels. When
anyone channel is changed, the COS detection circuit generate an
interrupt request signal.
DO circuit of PCI-7230, PCI-7234, and cPCI-7230
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