National Instruments CAN 372139B-01 - Manual (Page 49)

Chapter 5 Automotive Diagnostic Command Set API for LabVIEW
© National Instruments Corporation 5-23 Automotive Diagnostic Command Set User Manual
Output
diag ref out is a cluster containing all necessary diagnostic session
information. Wire this cluster as a handle to all subsequent diagnostic
VIs and close it using
Close Diagnostic.vi .
error out describes error conditions. If the error in cluster indicated an
error, the error out cluster contains the same information. Otherwise,
error out describes the error status of this VI.
status is TRUE if an error occurred.
code is the error code number identifying an error. A value of 0
means success. A negative value means error: the VI did not
execute the intended operation. A positive value means warning:
the VI executed intended operation, but an informational warning
is returned. For a description of the code, wire the error cluster
to a LabVIEW error-handling VI, such as the Simple Error
Handler.
source identifies the VI where the error occurred.
Description
Use this VI to open a diagnostic communication channel to an ECU for OBD-II. The CAN
port specified as input is initialized, and a handle to it is stored (among other internal data) in
the diag ref out cluster, which serves as reference for further diagnostic functions.
First, communication to the ECU is tried on the default 11-bit OBD CAN identifiers; if that
fails, the default 29-bit OBD CAN identifiers are tried. If that also fails, the VI returns an
error.
You can overwrite the default OBD CAN identifiers optionally with any other identifiers.
In general, it is not necessary to manipulate the diag ref out cluster contents.