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Lep
Senior
October 17, 2022
Solved

I use serial port for communication. When I close the serial port, the chart of the dashboard will continue to draw the waveform for 10s instead of stopping the drawing immediately. What is the reason for the delay?

  • October 17, 2022
  • 1 reply
  • 1858 views

My node design is shown in Figure 1. The serial port input is connected to a function Fecg_raw(), as shown in the second picture.

0693W00000Uo9KeQAJ.png0693W00000Uo9KyQAJ.png

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Best answer by stephane.legargeant

Hello

When the throughput of data is too high, there is some delay in the display. Some data can be buffered by the serial port driver, by node-RED backend and by frontend. When many data are sent from backend, there can be some delay in the display.

You can try to analyze what happens:

  • reduce the number of variables displayed or set a data rate limiter to see if it changes the delay.
  • slow down the data sent on the serial port to see if there is less delay
  • add some log function at different point to see when the data really stops in the flow.
  • check that port is closed immediately.

Best regards

Stephane

1 reply

stephane.legargeant
ST Employee
October 17, 2022

Hello

When the throughput of data is too high, there is some delay in the display. Some data can be buffered by the serial port driver, by node-RED backend and by frontend. When many data are sent from backend, there can be some delay in the display.

You can try to analyze what happens:

  • reduce the number of variables displayed or set a data rate limiter to see if it changes the delay.
  • slow down the data sent on the serial port to see if there is less delay
  • add some log function at different point to see when the data really stops in the flow.
  • check that port is closed immediately.

Best regards

Stephane

Lep
LepAuthor
Senior
October 17, 2022

Thank you for helping me since I used stm32cubemonitor.

I benefited a lot from your help.:beaming_face_with_smiling_eyes: