How do you separate serial sensor data from raw data string with "\" as delimiter?


I'm sorry to ask another question and I hope someone can help. I did not find a video or
another description how to handle this.

I get strings like "1\20\0003\5.5\........\n\r" (delimiter is "\"), comming from a sensor as a serial data stream any second via TCP connection. I would like to display certain values out of the string.

My question is, how can I separate the values from the string, separated by "\"?



'\' is asking for trouble.
It also serves as metadata (an escape character) in some contexts.

How about '|' instead, or send the readings in YAML format



Thanks for the example, it works perfect.

Also thank you for the hint about possible trouble with "\".
Unfortunately the sensor which delivers the delimiter is an existing HW.
I have to live with it.

Both thanks again, I appreciate your help, I learned alo today .

For good measure, also read the standard message Delimiter advice:

Please see the Delimiter article in FAQ

Be sure to use println() at the end of each message to send from the sending device, to signal end of message. Do not rely on timing for this, which is unreliable.

In the AI2 Designer, set the Delimiter attribute of the BlueTooth Client component to 10 to recognize the End of Line character.
Also, return data is not immediately available after sending a request,
you have to start a Clock Timer repeating and watch for its arrival in the Clock Timer event. The repeat rate of the Clock Timer should be faster than the transmission rate in the sending device, to not flood the AI2 buffers.

In your Clock Timer, you should check

  Is the BlueTooth Client still Connected?
  Is Bytes Available > 0?
     IF Bytes Available > 0 THEN
       set message var  to BT.ReceiveText(-1) 

This takes advantage of a special case in the ReceiveText block:

Receive text from the connected Bluetooth device. If numberOfBytes is less than 0, read until a delimiter byte value is received.

If you are sending multiple data values per message separated by | or comma, have your message split into a local or global variable for inspection before trying to select list items from it. Test if (length of list(split list result) >= expected list length) before doing any select list item operations, to avoid taking a long walk on a short pier. This bulletproofing is necessary in case your sending device sneaks in some commentary messages with the data values.

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Can you tell us the Make and Model number of the sensor please Robert.
Is it an RS232 type sensor?


Thank you very much for your very helpful hints! I'll take them into account continuing my
app design.

I can not really answer your question, because I designed the protocol by my own, many years ago. I'm using different sensors to measure temperatures, pressure, power, ... a.s.o.,
in my project. The sensors are located on different places in my facility. The sensors are
connected to own MC boards I build years ago. The collected data are feed into my local
network (TCP/IP Server). I have SW for my PCs to visualize and control the MC boards.
However, I lack of something similar for my Smartphone, so I decided to try MIT AI.

Thanks again for any help. Could be I'll be back soon with more questions :wink:.

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That's a super interesting Project. I think you have made the right choice in choosing App Inventor.