Error Checking And Responses - Basler A400K User Manual

4.3.1.1 Error Checking and Responses

ACK/NAK
When the camera receives a frame, it checks to see if the order of the bytes in the frame is correct.
If the FTF field indicates that the frame includes a BCC, the camera checks to see if the XOR sum
of the relevant frame fields matches the block check character. The camera also checks to see if
the number of bytes in the data field is equal to the number specified in the DataLen field.
If all checks are correct, an ACK is sent to the host. If any check is incorrect, a NAK is sent.
Byte Time-outs
The camera checks the time between the receipt of each byte in the frame. If the time between
any two bytes exceeds 0.5 seconds, the camera enters a "garbage state" and discards any more
incoming bytes. The camera remains in this state until it sees a new BFS.
Read Commands
In the normal case, when a read command is sent to the camera, the camera responds with an
ACK and a returned frame. The returned frame will contain the data requested.
If the camera receives a read command with an unknown or invalid address in the Address field
of the frame, it will respond with an ACK but will send no frame.
If the host sends a read command and gets no ACK/NAK, the host can assume that no camera is
present or the camera is in a "garbage state" for some reason.
If the host sends a read command and gets an ACK/NAK but does not receive a frame within
500 ms, the host can assume that there was a problem with the read command.
Write Command
In the normal case, when a write command is sent to the camera, the camera responds with an
ACK.
If the camera receives a write command with an unknown or invalid address in the Address field
of the frame, it will respond with an ACK but will not perform the write.
After a write command has been issued by the host, the host can verify the write by issuing a
corresponding read command and checking that the returned data is as expected (unless the
address is "write-only"). The host can read the Camera Status fields in the Camera Status inquiry
register (see page 4-9) and check the returned data to see if an error condition has been detected.
For many of the write commands listed in the tables on pages
only data within a specified range or a specified group of values is valid. If the data
in a write command is not within the allowed range or specified group of allowed val-
ues, the camera will not execute the write command.
Basler A400k
DRAFT
Configuring the Camera
4-34 through 4-44,
4-49