National Instruments CAN 372139B-01 - Manual (Page 287)

Chapter 6 Automotive Diagnostic Command Set API for C
© National Instruments Corporation 6-123 Automotive Diagnostic Command Set User Manual
Output
DTCs
Returns the resulting DTCs as an array of structs:
typedef struct {
unsigned long DTC;
unsigned long Status;
unsigned long AddData;
} TD4;
DTC is the resulting Diagnostic Trouble Code. For the default 2-byte DTCs, use
ndDTCToString to convert this code to readable format as defined by SAE J2012.
Status is the DTC status. Usually, this is a bit field with following meaning:
Bit Meaning
0 testFailed
1 testFailedThisMonitoringCycle
2 pendingDTC
3 confirmedDTC
4 testNotCompletedSinceLastClear
5 testFailedSinceLastClear
6 testNotCompletedThisMonitoringCycle
7 warningIndicatorRequested
For OBD, this field usually does not contain valid information.
AddData contains optional additional data for this DTC. Usually, this does not
contain valid information (refer to DTCDescriptor ).
len
On input, len must contain the DTCs array length in elements. On return, it contains the
number of valid elements in the DTCs array.
success
Indicates successful receipt of a positive response message for this diagnostic service.
Return Value
The return value indicates the function call status as a signed 32-bit integer. Zero means the
function executed successfully. A negative value specifies an error, which means the function
did not perform the expected behavior. A positive value specifies a warning, which means the
function performed as expected, but a condition arose that may require attention.
Use the ndStatusToString function to obtain a descriptive string for the return value.