How to process the continuous serial data (Serial data frame time is 250ms)

[Sumit35]

Hi,

I need a help to "process the serial Hex data" serial data rate is 250ms.

I am able to read the serial data and right now, we have the Concatenated Hex string but not able to Spit this string the modify and write again.

Each 250ms i get new data frame,data frame length is 1st frame 13bytes, 2nd frame 17bytes and  3rd frame 17bytes * no of module.We are develope the application to change the perticular bytes of each frame and send it again.

Mach pattern,Replace pattern all string find and replace fundamental tried not working.

Please help.

[crossrulz]

Where is the data coming from?  Is there anything in the frame to indicate what the frame is?  Is there a start character (often 0x2)?  Is there a checksum to make sure you read the frame right?

[Sumit35]

Hi,

Yes,each frame having multiple CRC and Total frame also having stating and end frames and each frame having the start & end bytes.Please look into the attached Description.

[crossrulz]

The way I see it, we first need to synch up to the 7F18.  Once you find the 7F18, you know how many characters are in a line and you know how many lines are to follow.  So you can just read that number of bytes once you get synched up.  You could do the synching in a simple loop that just reads 1 byte at a time.  Compare the previous byte and the current byte to 7F18.  Once you have a match, read 11 more bytes to complete that line.  If you want to make sure, you should also perform the CRC check in that line.

[Sumit35]

Hi,

Thanks for your valuable suggestion but we are tried all possible scanrios with "Match & Replace string" Or "Replace string" Or "Split String" but data from serial port is so fast replace,match loop is not able to execute.Output of all is showing blank.We get the 1 frame of 250ms,in that 1st  subframe 7F18 to 7F22 then no. of 7F22 to 7F22 subframe and last frame is 7F20.Please find the attached different  VI.

[crossrulz]

I immediately see 2 really big issues.

1. Since you are dealing with binary data, turn the Termination Character off.  There is a boolean input on the Configure Serial Port to do so.  It is on by default.

2. Your VI is running slow because you have a constantly growing string.  Once you find a frame, remove it from the string that you are storing in the shift register.

[Sumit35]

Hi,

Would you please make the chnages and share to me?

[crossrulz]

I thought about this way too much...

This should get you started for getting the frame itself.  I have not tested it at all.