Table 11G CAN-bus Messages
11.2.2.4.1 Message: Result Codes
This message is transmitted after each test.
The test result is expressed as a set of codes in the selected Test Format (ISO4406, NAS1638 etc.). The test result
message is always 8 bytes long, with the result codes packed as follows:
NOTE: The ‘basic’ class is the highest of the individual size classes.
ISO4406 only defines codes for the first 3 sizes 4, 6 and 14µm. we extend the concept to cover the other
sizes. This allows limits to be set on the number of large particles, even when using the ISO 4406 coding
system.
11.2.2.4.1.1 Special Values
The result codes use a few ``special’’ values in order to represent codes that are not simple numbers.
The NAS1638 standard defines classes ``00’’ and ``000’’, these are classes ``cleaner’’ than class 0. We represent
these using signed integers of value -1 and -2 respectively (these will appear as 255 and 254 if read as unsigned
integers).
11.2.2.4.2 Message: Status
The message is transmitted every 1 second so that it can be used as a ``heartbeat’’.
However if no test has been performed yet, the CMS will wait until it sees other CAN-bus activity before sending
anything.