Capture Buffer Filtering

Posted: 13 years ago Quote
I am evaluating your 1480A for a USB communication problem we are investigating. I'd like to understand what HW Capture Filtering modes are available with the 1480A unit. The particular test we need to run is described below. Our USB communication drops out randomly about once every few days of continuous operation. We want to capture all the USB full speed packets that are larger than 2 bytes in length. Our system generates a lot of small 2 byte data packets which we are not interested in. If we don't filter these 2 byte packets out of the captured data then the buffer will fill up in less than a minute. That leads me to the question: Can the 1480A unit do HW capture filtering so that these 2 byte data packets don't fill up the FIFO buffer?

Our system operates in Full Speed rate.
Four or more systems are connected to a USB hub and the hub is connected to a PC. The hub to PC USB link is at the High Speed rate.
The 1480A would be inserted in-between the hub and the PC so it can monitor the packets from all of our systems.
Because of the infrequent nature of the USB communication problem this test will need to run continuously for as long as 5 days.
The amount of data generated by this test setup is ~5MB per hour, providing we filter out the 2 byte data packets from the capture buffer.
Posted: 13 years ago Quote
No, we currently don't support hardware filtering because this would substantially raise the price of the 1480A unit. This is a little used feature that most users would not pay extra for. Therefore, we are considering adding all similar requested advanced features to a special for-pay software upgrade.

Note that the current 1480A software will allow you to capture the data but the capture file will be very big so the parsing time for analyzing the data will be very, very long.

The 1480A software in real-time uploads data from the 1480A hardware at the same time data is captured. The hardware FIFO is only there to buffer the data. As long as the data captured is less than around 20 MB/s then the uplink speed shold be fast enough to avoid a capture FIFO fill-up.