National Instruments CAN 372139B-01 - Manual (Page 164)

Chapter 5 Automotive Diagnostic Command Set API for LabVIEW
Automotive Diagnostic Command Set User Manual 5-138 ni.com
Output
diag ref out is a copy of diag ref in. You can wire it to subsequent
diagnostic VIs.
data out returns the vehicle information from the ECU. You can obtain the
description from the SAE J1979 standard.
success? indicates successful receipt of a positive response message for
this diagnostic service.
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.
# items is the number of data items (not bytes) this service returns.