What is the significance of :
- Request Specific Address
- Request Specific Address on Fault
- Route Data to PVA Guage
Also if I want to use particular J1939 message, let’s say “J1939.VD.Total Fuel Used”, then what all things I need to configure in display apart from mapping that message to variable?

In display we can create variable but while creating a new variable, it just asks for “New Numeric Variable” but doesn’t let us specify/know the exact type of variable like float, integer, etc..How to determine this?

Thanks & regards,
Shruti

Hi ShrutiK,

Those three items are touched on in the PowerVision Studio 2.3 Core manual on pages 38-39 of the PDF. Here are more detailed explanations.

• Request Specific Address
  Basically, if "Request Specific Address" is checked, the display will request any PGNs marked as "Request" in the J1939/NMEA database that are mapped to the device. For instance, you mapped the Total Fuel Used (SPN 250) parameter to the VD device displayed in your image. If you checked "Request Specific Address", the display would periodically send a request for PGN 65257 from address 0 (the source address of the VD device). This is because PGN 65257 contains the Total Fuel Used parameter and is marked as "Request".
  
  If you wanted to request SPN 250 from all devices on the CAN network, you can check the "Send Global ISO Request" checkbox on the J1939 application (see image). This would cause the display to send a request for PGN 65257 to the "global address" of 255 (0xFF), and all devices on the CAN network should either respond with the requested PGN data, or respond that they don't support that PGN.

  

  J1939.png (28.52 KiB) Viewed 186 times

• Request Specific Address On Fault
  The behavior is very similar for the "Request Specific Address On Fault" function. When you instruct the display to request stored (DM2) faults, it will send out a DM2 request message to the specific address of each CAN device that has the "Request Specific Address On Fault" checkbox selected.
  
  Likewise, if the "Send Global DM2 Request" checkbox is selected, the display will also send a DM2 request message to the "global address" of 255 (0xFF), which should prompt all devices on the CAN network to respond with their stored faults.
• Route Data to PVA Gauges
  If you have the "Route Data to PVA Gauges" checkbox selected, the display will pass along parameter data to any PVA gauges connected on the RS485 bus. For instance, if you had the Engine Speed (SPN 190) parameter mapped to the VD device, and you also had an RPM PVA gauge connected to the display's RS485 bus, the display would pass along the RPM data to the PVA gauge so that it would show the RPM value being received on the CAN bus. The Address field can be either 0 for local PVA gauges, or 1 for remote PVA gauges (that field is not at all intuitive). An Address of 0 works for most applications using PVA gauges.

As described above, in order to use the Total Fuel Used parameter, you'll have to make sure that either "Send Global ISO Request" is selected on the J1939 application (should be selected by default), or "Request Specific Address" is selected. Some devices don't respond to global PGN requests, and specific requests must be sent. A request message is required to get the Total Fuel Used parameter data because PGN 65257 is marked as Request (and is defined as request-only in the J1939 standard), so the VD device shouldn't be broadcasting that particular PGN until it is requested.

Currently, all of the database variables on the display are of type "double".

Let me know if you have any more questions or if I need to provide any additional clarification.

Regards

Thanks for the clarification.

Is there any plan to have support for different type of numeric variable instead of having only double type of variables?

Thanks & regards,
Shruti

Yes, different numeric variable types is a feature that is on our roadmap, but unfortunately it hasn't been slated for a specific release at this time.

Thanks