Adimec Camera Link OPAL Series, Operating And Users Manual

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OPERATING AND USER MANUAL OPAL-FAMILY
80
REFERENCE
Data flow characters 11.3.3.
The communication protocol uses data flow control characters to identify a message and for
acknowledgement.
The following data flow characters are defined:
CHAR DEC DESCRIPTION
NUL 0 NUL character, is ignored
STX 64 start of message identifier
ETX 13 end of message identifier
ACK 6 positive acknowledgement
NAK 21 negative acknowledgement
Used ASCII control characters Table 11.6:
Message Format 11.3.4.
Command and data are combined in a message. A message starts with the STX character followed
by the message content. The message ends with an ETX character. The characters allowed in the
message content range from decimal 32 to 255.
Format: STX <message content> ETX
Message acknowledgement 11.3.5.
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 11.3.6.
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 sent back to the host
system.
Communication timing 11.3.7.
The time between the successive characters making up a message is not limited. The camera
however, when transmitting a message to host system, has a time interval between successive
characters of less than the time required for a single character to be transmitted.