why does the left part of curve in Oscillosope disappear when using CAN communication?

[ChenBowen]

Dear Expert:

    I am using Freemaster2.5, Why does the left part of curve in Oscillosope disappear when using CAN communication?   And more, the curve sometimes suddenly  stops for a second and then moves on, making the curve strange as expected.    

    If using JTAG communication, these issues all resolve , but we need to use CAN in project.

[MichalH · Accepted solution]

Hello,

most probably, this is caused by a fact that CAN communication is faster and there is a limited number of points configured for the Oscilloscope graph. 

Go to oscilloscope properties and see the "Buffer" settings (I do not have a screenshot for old version 2.5). The number set there defines the maximum number of points the graph will be able to handle. You can increase this number.

Also, most probably, you have the Period set to 0ms (fastest possible). This means that the fast CAN is able acquire the maximum number of points in graph quicker than over a serial line. If you would set the period to 10ms or so, both CAN and serial would be sampling at the same speed and the graph would behave the same.

Regards,
Michal 

[ChenBowen]

Thank you !