Under review

Handling Dynamic Length Text Parameters in the middle of a PGN (64582)

705David 1 year ago in IQANdesign updated by Gustav Widén (System support) 1 year ago 5

I'm working with a TPMS System and there is a PGN 64582 (0xFC46) which has SPNs in order:

a = Number of Tire Sensors

b = Tire Sensor Tire Number

c = Tire Sensor Location

d = Tire Sensor Identification Number (ASCII with * delimiter)

The Digital Annex says d mentioned above is variable length from 0 to 200 bytes followed by "*" delimiter.

The SPNs are received in order a,b,c,d,b,c,d,b,c,d,...etc (to the number of tires on the machine).

I have attempted to set up the JFIN using JPINs for everything but the Sensor Identification Number, which I use a TPIN with a delimiter of 42 (ASCII *)

The first set of a,b,c,d SPNs I know the bit offset for because a,b,c are fixed length. After the first TPIN, the data no longer lines up with my bit offsets and I can't set the bit offsets of the JFINs to Dynamic.

Is there a way to set up the Bit Offsets to account for a variable length text parameter in the middle of the SPNs?


With existing functionality, I cannot think of a way to get this to work. 

Out of curiosity, what would SPN 6966 be used for in the application? 

SPN 6966 would provide the Tire Pressure Sensor's ID Number for each given tire location.

ID's would be provided on the HMI or in the logs so that service technicians could replace the sensors reporting problems. The technicians are equipped with hardware for scanning a sensor when they are not paired with a vehicle.

If we were able to set Dynamic Bit Offsets for JPINs after a delimited text parameter, it would make handling this very easy, but that is not the case.

From the IQAN Design documentation it appears the variable sized TPINs are expected to be the last SPN in the Frame.

Yes, the variable length text must come last in the message. 

For the information to the service technician, what about showing a clear text description of the Tire Location instead of Tire Pressure sensor ID? 


Hi Gustav,

We aren't monitoring this message now because of the complications with text handling in IQAN.

We decided to remove the ID from the display entirely and the technicians now need to use a separate tool for checking tire positioning.

One suggestion for future upgrades to IQAN is better text handling support.



Under review

Changed topic from Question to Ideas.