“All beginnings are hard! When you want to use an oscilloscope to analyze a problem, you must have thought about it. How can I catch the problem? Of course, only after the arrest can we carry out the following analyses, otherwise everything will be empty talk. This article will take you three best methods to catch the exception.
All beginnings are hard! When you want to use an oscilloscope to analyze a problem, you must have thought about it. How can I catch the problem? Of course, only after the arrest can we carry out the following analyses, otherwise everything will be empty talk. This article will take you three best methods to catch the exception.
1. Rolling mode
You may seldom use the scroll mode, but it is the easiest and crudest way to analyze problems. All you have to do is to determine how long the anomaly will occur and whether the sampling rate is sufficient. If an abnormality occurs within 5 seconds, set the scroll to collect data for 7 seconds and then stop. Under the premise that the sampling rate is sufficient, I believe the problem will not escape your palm.
Figure 1 Rolling acquisition voltage drop waveform
The rolling mode is “no dead zone”, any abnormal problems can be caught, but the premise is that the sampling rate is high enough. As shown in the figure above, the sampling rate is 50MHz. When the abnormal frequency exceeds 25MHz, it is difficult to collect accurate waveforms. The rolling mode of ZDS4000 supports a sampling rate of up to 500MHz, and the longest data acquisition time is 7.2 hours (the sampling rate at this time is 20KHz).
2. Rolling mode + online monitoring
Anything has advantages and disadvantages. Of course, scroll mode has its disadvantages: it does not support triggering and automatically stops after triggering. That is, when using scrolling to analyze the problem, it is necessary to use the human eye to determine the abnormality, and after catching the abnormality, manually stop sampling, which is sometimes very difficult. Here is a recommended method for online abnormal monitoring. First, turn on the rolling measurement function of ZDS4000, and then read the measured value through the network to determine whether there is an abnormality, and finally stop the oscilloscope sampling. Taking the voltage drop as an example (the peak-to-peak value is 5V when there is a problem), the oscilloscope settings and python monitoring script are as follows:
Figure 2 50ms rolling mode, peak-to-peak measurement, 500MHz sampling rate
Figure 3 Python online monitoring source code
The online monitoring method can make up for the shortcomings of scrolling to a large extent, but it is not a panacea. If the measurement function provided by the oscilloscope cannot detect errors, it is very difficult. Fortunately, ZDS4000 provides more than 50 measurements. Most errors can be detected.
3. Trigger + segmented storage
Triggering is one of the most frequently used functions of the oscilloscope. The specific settings are more complicated. You can operate according to the following ideas:
Which channel is used for triggering? Set the trigger source.
What does the abnormality look like? Set the trigger type and trigger level.
The anomaly disappeared in a flash? Turn on the template trigger and move the template to the area where the abnormal waveform is located.
How to stop automatically after catching an exception? Click Single to run, and it will stop automatically after catching an exception.
How to collect anomalies multiple times? Set Normal trigger, click RUN to run, manually stop after multiple acquisitions, open segmented memory (Seg), you can browse all the caught exceptions.
Figure 4 Segmented browsing of abnormal waveforms
In the non-scrolling mode, there is a dead zone in the sampling, and abnormalities in the dead zone will not be caught and will not be displayed on the screen. The dead time can be confirmed by the refresh rate index of the oscilloscope. The higher the refresh rate, the smaller the dead time and the higher the accuracy of catching abnormalities.
Even though the problem is strange, as long as it is caught correctly, it is not far from solving the problem! The ZDS4000 series oscilloscope has the advantages of 512M deep storage, high refresh rate, and true parameter measurement. It covers all the functions of the above three methods and can help you improve the efficiency of problem-solving.