how to aquire xPC data in a triggered manner

Hello,

 I would like to log some signals in xPC, preferentially to file using xPC file-scope. However, I would like to log data only at the occurrence of a trigger signal and would very muck like to have one file per trigger event (i.e., each time the trigger goes high, make a new file called like xxx001.dat and log data until trigger gets low. At second trigger event log to xxx002.dat and so on). 

Dividing the recorded data is essential as logging everything to one file would make this file huge (!) and make data extraction difficult too...

Any ideas how I can do so? Alternatives would help me too.

 Thanks in advance.

Answer 1

[Suneesh]

1 "have one file per trigger event": For this I am not able to think of a way apart from having several File Scope blocks each of them getting triggered at a different point in time.

2. If your main concern is having files that are too big then maybe you can use 'Dynamic file name enabled'. This enables splitting the files. Look for 'Dynamic file name enabled', 'Max file size in bytes' and AutoRestart in:

http://www.mathworks.com/help/xpc/io_ref/scopexpc.html#f51-15783

[Istvan]

Thank you very much for your answer!

The idea is to record the response of a system to many inputs. Thus, for each input I would like to record the answer to a different file. The number of scopes is limited, so I cannot use thousands of them... The issue is, if all responses are merged into the same file, it gets large and difficult to process. That is why I wanted - for the sake of simplicity and ease - to have each response separated.

Therefore, using the splitting on file size (Dynamic file name enabled) makes life hard, as it does not give me one response per file but just chops up the data, making it more difficult to extract afterwards.

The only way I can think of, is to indeed use the Dynamic file name enabled and record both the response and the input. Than go over the files sequentially and extract the responses one by one, in post-processing, using the recorded input signal to try to separate individual responses (trials)....

[Istvan]

.. obviously another way is to restart physically the xPC model each time, but that takes forever.

[Suneesh]

The only other solution I can think of is to write your own C MEX S-Function which internally uses C commands like FOPEN etc to write to files. I feel you can name the files in you code as well. If you are not familiar with S-Functions this is not going to be trivial.

http://www.mathworks.com/help/simulink/sfg/example-of-a-basic-c-mex-s-function.html

[Istvan]

Right, thanks :)