Oscilloscope APP shows delay in signal tracking

[jh123]

Dear Community,

our sales partner is recently testing with our Oscilloscope APP and found out a magnificent delay in signal tracking.

In the picture, the test engineer is tracking S-0-0047 Position Command Value and S-0-0051 Position Feedback Value.  For visualizatoin, he used both Oscilloscope APP in ctrlX CORE and oscilloscope function in ctrlX Drive engineering to track the signal values.

After comparison, the result shows that there is an apparent delay of signal incoming about 5~6 cycle time in the Oscilloscope APP which is running on ctrlX CORE as real-time task. They also tried with ctrlX CORE X3 and X7, and both hardware gave the same result. 

Automation Core 1.20.1 / Oscilloscope APP 1.20.1 / EtherCAT Master APP 1.20.1

Is this a bug or any configuration mistake? 

Thanks,

Hui

[kde · Accepted solution]

This is not a bug neither a configuration mistake, but a conceptual error.

1. First of all, Oscilloscope is a signal collector, it only displays the measurement
2. The sources of these two devices are different. The signal on Drive Engineering is drive's own internal cycle. The signal on the fieldbus node of ethercatmaster is the drive signal obtained by ehtercatMaster through the mailbox protocl
3. The mailbox protocol is a non-real-time protocol, so the signal of ECM obtained is a NRT signal relative to Drive, so thet will be out of sync and there will be delay
4. The so-called synchronization refers to the apps on the ctrlX CORE(ECM. MOT, OSC...).  thet are all scheduled by the scheduler and they are synchronized in real time

tip:

if you want to use Oscilloscope to measure drive signals, please use OSC-V-0206 with DCA app

[yzpguest]

Thank you very much for your answer. I still have some questions.

If the CtrlX device supports these two communication methods:

Service Channel: Used for device configuration or parameter setting. It allows access to device parameters through the IDN (Identity Number) for configuring or modifying the parameters of servo drives.

Process Data: Used for real-time data exchange, such as control commands and device status feedback. This method supports efficient and low-latency data transmission, suitable for control applications that require a rapid response.

If the position under this data layer communicates via the process data pathway

If the oscilloscope is synchronized in real time.

When the oscilloscope listens to the data.

Will there be a delay of five cycles in this case?