J Daniel Martinez C

Important changes to forums and questions

All forums and questions are now archived. To start a new conversation or read the latest updates go to forums.mbed.com.

8 years ago.

I want to tap an usb device for auditing, is that possible? without interrupting the connection.

Any ideas?

What do you mean 'tap a USB device'? Just monitoring whatever the USB device is sending?

posted by Jan Jongboom 11 Apr 2016

1 Answer

Sanjiv Bhatia
8 years ago.

I think you mean like a bus sniffer for the USB connection to spy on the traffic ? Believe there are USB s/w monitor tools for Windows or you could consider a relatively low cost USB bus analyzer. What is the USB bus speed you wish to monitor ?

What is the interface on this dynamometer ? Is it RS232 ? RS422 ? RS485 ? How long is the cabling ? Do you have a spec sheet that details the interface of this dynamometer ? If RS232, you are limited on the cable length vs. speed of the transfer. You can go longer with RS422 or RS485 but must be aware of the environment. More details after you confirm which type of interface you are using. Also, this setup loses connection once in a while after running ?

115200

posted by J Daniel Martinez C 11 Apr 2016

Hi. Sorry - meant to ask what speed of USB you wish to monitor. USB has the 1.1, 2.0 FS, 2.0 HS and then 3.0, 3.1 SS. For each level, the cost and complexity of the bus tool will increase. For example, if you are USB 2.0 FS (12 Mbps) then there are many low cost bus analyzers you can purchase.

Also, be sure where you wish to monitor the signals. Are you interested to view the USB packets ? If yes, then you need to review USB Bus analyzers - recommend a hardware tool so you can view the timing, packets, etc.

If you wish to view perhaps the RS232 signals @ 115200 then you will need a RS232 signal / bus analyzer (check some UART tools and be sure to check the voltage levels of the UART tools as some may be only for low voltages and NOT for RS232 voltages).

posted by Sanjiv Bhatia 11 Apr 2016

USB 2.0

posted by J Daniel Martinez C 11 Apr 2016

I hava a dynamometer that sends all the values from the motor, i already try with a splitter cable but the signal is not enough, the system detects its the signal is lost. What i need to do is to capture those signals without interrupting so i can audit them so I can prove that the user is not altering the information in some way

posted by J Daniel Martinez C 11 Apr 2016