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Chapter 4:
The APIs in this section of
being used in another instance, retrieving information from firmware, opening and
closing a hardware, and connecting/disconnecting a demo camera.
Once the library has been initialized, all hardware that is powered on and connected to
the host computer will have a corresponding hardware ID. Accessing hardware is as
simple as opening available hardware using its corresponding ID.
A demo camera is a software-simulated camera. This allows program development
without a camera connected. A demo camera can be instantiated by choosing a
particular camera model and connecting it. Once connected, it can be interacted with
as any other camera.
Once hardware (possibly a demo camera) is no longer used, it should be closed.
The following factors affect hardware availability to the program:
Basic information identifies the model, computer interface, and serial number of the
hardware (as well as the sensor for cameras.)
Additional information contained in the hardware's firmware can be read if the specified
hardware is connected and provides the logic program IDs and revision levels. This
information may not be available for hardware that has been opened elsewhere (in
another process).
Identification APIs
NOTE:
It is recommended that the Advanced API be used for device
discovery if it is necessary to detect newly connected
hardware after the library has been initialized.
•
Connectivity
In order for hardware to be detected by the program it must be:
— Connected to the host computer;
— The hardware must be powered on.
•
Open Elsewhere
Hardware can only be controlled by a single instance of a program. If hardware
has already been opened by another program (i.e., it is open elsewhere,) it is
unavailable and cannot be used until it is closed.
deal with determining what hardware is available or
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