Hardware Information: Dual GM J1850 (DLC) card

External D-9 connector pinout

Pin # Channel Assignment
021J1850 Bus
032J1850 Bus
05BothV- In/GND
09BothV+ In

BUS termination requirements

(None.)

Event definitions


The following values may be transmitted as FT_EVENT type GCProtocol frames.
The event value will be in the event field of such a frame.
Note: Please see the include file dev_dlc.h for numeric values of the following symbols.

Event nameEvent meaning
GDLCRXOVERReceiver overflow
GDLCCRCERRCRC error detected
GDLCINCOMPBYTEIncomplete byte detected
GDLCBTERRBit timing error detected
GDLCBREAKBreak received
GDLCNETFAULTNet fault detected
GDLCTXUNDERTransmit underrun
GDLCARBLOSTArbitration lost
Please also see generic events for non card-specific events.

Card-specific IOCTL definitions


These values are used with the CMD_CARD_IOCTL command.
Please see the include file dev_dlc.h for numeric values of IOCTLS and data field bit assignments.

IOCTL nameFunctionData field length/purpose
GDLCGETFOURX Get DLC 4x-speed flag1 data byte returned: current 4x-speed flag
GDLCSETFOURX Set DLC 4x-speed flag1 data byte: new 4x-speed flag.
Set values valid only after next INIT IOCTL.
GDLCGETLOAD Get load resistor flag1 data byte: current load resistor flag
GDLCSETLOAD Set load resistor flag1 data byte: new load resistor flag value
Value valid immediately.
GDLCSENDBREAK Send a BREAK on the J1850 busNone
GDLCABORTTX Abort current transmissionNone
GDLCGETHDRMODE Get header mode1 data byte: current header mode
Controls number of header bytes.
Possible modes: zero, one, three header bytes; one byte OBD mode; auto mode.
GDLCSETHDRMODE Set header mode1 data byte: new header mode

FT_DATA frame stat field definitions:


The following bits may be set in the stat field of FT_DATA messages.
GDLCSTAT_IFR is set when the message is in-frame response data.
GDLCSTAT_NB is set when the normalization bit is set on a received message.