No dropped frames with NI-USB 8473?

[PhilippeVDN]

Hello

We do a project in our school with the NI-USB 8473 interface.  In the specifications, you can see there is a resolution of 1 microsecond and there are no frames dropped.

Why is there in the busmonitor then only an update rate of 100 ms?

When we read in LabVIEW, we can approx. read 1/2 of all the identifiers. Can anyone tell us where this information is dropped, when it's not in the hardware?

Can it be the speed of the computer? We use a laptop with 1.55 GHz with 2 GB of RAM.

We read the CAN-bus of a toyota RAV4 and we only see 52 of the 104 identifiers.

Can someone tell us more about this?

Thanks

[Paul M.]

Philippe,

The 8473 will definitely get all of the vehicle data to your PC, no problem.  It's not a whole lot of data - vehicles operate at 500kbps, which is only 62.5Kbytes/second at the maximum, barely any more data than a DSL modem.

The bus monitor is designed to let you visually see the data, so it groups together the frames for you in software.  While it is updating at 100ms, all of the data is represented (watch the # of frames received column).  If you want to capture ALL of the data for offline analysis, you can use the bus monitor to log the data to a file and examine the data from there or run one of the CAN logging examples.

What identifiers are you expecting? Which aren't showing up?  Keep in mind that many modern vehicles have multiple CAN busses and that it is possible not all of the data is being sent out of the CAN network you're connected to. I am assuming you're connected through the OBD port.

What is the goal of your project?