Hardware Information: Dual j1708 card

External D-9 connector pinout

Pin # Channel Assignment
012J1708 Bus+
021J1708 Bus+
03BothSIGNAL GND
05BothV- In
062J1708 Bus-
071J1708 Bus-
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
GJ1708RXOVERReceiver overflow
GJ1708FRAMEReceiver framing error
GJ1708BREAKBreak received
GJ1708COLLISIONBus collision detected
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
GGETERRLEV   Get channel error reporting level1 data byte: current error reporting level
GSETERRLEV   Set channel error reporting level1 data byte: new error reporting level
Value valid only after next INIT IOCTL.
GJ1708GETBITRATE   Get the current bit rate   4 data bytes returned: current bit rate in host byte order (normal x86 format)
GJ1708SETBITRATE   Set a new bit rate   4 data bytes: new bit ratein host byte order (normal x86 format).
Effective only after the next INIT IOCTL.
GJ1708GETPRIORITY   Get the current msg priority   1 data byte: current message priority
GJ1708SETPRIORITY   Set a new message priority   1 data byte: new message priority
Effective immediately.


FT_DATA frame extra data:

There may be zero, two or three bytes of extra data. The first byte of the extra data contains flag bits that determine the meaning of the remaining bytes. The flag bit values are:
The flag bit values may be combined as desired. If bit zero is set, the second byte is the checksum to be used instead of the driver calculated value.

If bit one is set, the second or third byte contains the priority to be used for the message, overriding the default priority. If bit zero is set, the priority is in the third byte, if bit zero is not set, the priority is in the second byte.

If bit one and two are set, the priority in the second or third byte is used for the message and is stored as the default priority for all of the following messages. If bit two is set and bit one is not set, the default priority is used for the message and the default priority is not changed.


Message Checksum

The driver calculates the checksum for each transmitted message. That checksum may be replaced by one in the extra data field as described above. This is normally done to create a bad checksum.

If the received checksum is correct, there is no indication. If the wrong checksum is received, the received checksum is the only byte in the extra data field.