CAMERA LINK Q-2A340, Operating And Users Manual

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OPERATING AND USER MANUAL QUARTZ SERIES
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Message acknowledgement 5.2.4.
After receiving a message, the camera responds with an acknowledgement character. This can be an
ACK character (positive acknowledgement) or a NAK character (negative acknowledgement).
The ACK response is given when the received message was understood (the content of the message
is not considered).
The NAK response is given when the received message was not understood, which may be the case
when invalid characters are received as message content, or the message overruns the camera
receiver buffer capacity.
Reply messages 5.2.5.
When a message is sent to the camera that requires data to be transmitted back to the host system,
this data is packed in a message and is sent to the host system after the positive acknowledgement
(ACK) character. When the camera responds with a NAK character no data is send back to the host
system.
Communication timing 5.2.6.
The time between the successive characters making up a message is not limited. The camera
however, when transmitting a message to the host system, has a time interval between successive
characters of less than the time required for a single character to be transmitted.
Host system requirements 5.2.7.
After transmitting a message to the camera, the host system must wait for the camera to reply with an
ACK or NAK character. To prevent lock-up, the wait time for the response must be limited by a time-
out period. After not receiving an ACK or NAK character after the time-out period has elapsed, the
host system must consider the transmitted message as not being received.
The time-out time to be used for the camera should be at least 200 ms.
Under normal conditions, a NAK or no response from the camera results from damage of the
transmitted characters due to noise or communication link hardware problems. In such case, the
host system should transmit the message again. The number of repeated transmissions after a NAK
response or no response must be limited by a retry count to prevent lock-up.
If the camera is still responding with a NAK character after the maximum number of retries of
the transmitted message have been sent, the communications channel should be considered
malfunctioning or too noisy.
When the maximum number of retries of the transmitted message has been reached and the camera is
still not responding, the communication channel should be considered disconnected or the camera not
being powered or malfunctioning.
Camera Link interface standard 5.3
Introduction 5.3.1.
Without getting into detail on the Camera Link standard, this section discusses the mechanics of the
serial communication channel.
Available Camera Link serial software enhancements in the form of Dynamic Link Library files will
greatly simplify the setup of a communication channel.
Both camera manufacturers and frame grabber vendors have issued these DLL files which will provide
standard C, API and native Visual Basic support, so that applications written in C or Visual Basic can
communicate serially with Camera Link cameras.