Experimental Physics and
Industrial Control System

    I could use some help formatting an output from a waveform record that uses stream.

 

My IOC is built with:

    Base 7.0.4

    Asyn 4.40

    StreamDevice 2.8.8

    SNCSEQ 2.2.6

 

Here is the record definition.

 

record (waveform, "$(P)$(R):ScanListC")

{

   field(DESC, "Send configuration command.")

   field(DTYP, "stream")

   field(OUT,  "@daq970A.proto set_scan_route $(PORT)")

   field(NELM, "22")

   field(FTVL, "STRING")

}

 

Here is the stream protocol.

 

set_scan_route {

   separator=",";

   out "ROUT:SCAN(@%d)";

}

 

Here is the part of the SNL program that I use to put data into the waveform record.  It may put anywhere from 0 to NUM_CHANNELS (currently 22) integers into the waveform record.

 

int scan_list[NUM_CHANNELS];

assign scan_list to "{P}{R}:ScanListC.VAL";

 

ss set_scan {

 

   state construct_list {

                

      when (set_scan_list == 1) {

 

         set_scan_list = 0;

         counter = 0;

      

         for (channel = 0; channel < NUM_CHANNELS; channel++)

         {

            pvGet(channel_include_in_scan_901A[channel]);

 

            if (channel_include_in_scan_901A[channel] == 1)

            {

               scan_list[counter] = channel + 101;

               counter = counter + 1;

            }

         }

         pvPut(scan_list);

      

      } state construct_list  

   }

}

 

Here is the output on the asyn port when that part of the program runs after I have selected channels 101 and 103 on the MEDM screen and clicked the “Set Scan List” button.

 

ROUT:SCAN(@101,103,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)

 

What I want the output to be is:

 

ROUT:SCAN(@101,103)

 

 

Is there a way to have stream reject the zeros that are not valid data?

Interesting little problem, thanks for including all the elements to describe it.

I’m guessing that StreamDevice uses the current length of the waveform (NORD) as the number of elements it should convert. If that’s true then your problem becomes a sequencer question instead of a Streams question: Is it possible to pvPut() an array value with fewer elements than the array variable (local and remote) is configured to hold?

Unfortunately from the source code it looks like the answer is no; the array length used inside the pvPut() call is always set to the NELM value of the waveform record you’re pointing to.

I suggest you add a subArray record to hold the array that your SNL puts to, and have the SNL code write the channel count to the NELM field before putting the array data to its VAL field. The subArray will strip off the unwanted elements when it processes, and you can then pull the result into a waveform or aao record for StreamDevice to output to your hardware.

- Andrew