Re: Process aSub record on arrival of data

[Matt Rippa via Tech-talk <tech-talk at aps.anl.gov>]

Thanks for the help Andrew and Ralph!

This monitor style works as you say(changes below).  It was confusing when I put a camonitor on RX.A it only shows the latest array --but doesn't update as new data arrives.

Subsequent cagets of RX.A would show the new data. Also, a camonitor on RX didn't update and I assumed it should if the timestamp and TIME field were updating.

When I set RX.TPRO  to 1, I saw the record is processed every time TX processes. I added a routine on  RX.SNAM and everything is working fine.

Is there an easy way to measure statistics (flight time and jitter) of a modest payload?

We're trying to see if we can meet a 200 usec requirement to send corrections from our wavefront sensor to our secondary mirror.

We have 1 Gb network switches.

This is currently accomplished with reflected memory hardware (VMIC 5588).

-Matt

=====Setting RX.TPRO 1 Confirmed the RX processed every time TX processed=====

#seq sncxxx,"user=mrippa"
epics>  
epics>  
epics> scanOnce: dbProcess of 'test:RX'
scanOnce: dbProcess of 'test:RX'
scanOnce: dbProcess of 'test:RX'
scanOnce: dbProcess of 'test:RX'
...

===========IOC A==============

record(aSub,"test:TX")
{
   field(INAM,"TxInit")
   field(SNAM,"TxTransmit")
   field(FTVA,"DOUBLE")
   field(NOVA,"10")
   field(SCAN,"1 second")
}

static long TxInit(aSubRecord *precord)
{

   srand ( time ( NULL));
   if (mySubDebug)
       printf("Record %s called myAsubInit(%p)\n",
              precord->name, (void*) precord);
   return 0;
}

static long TxTransmit(aSubRecord *precord)
{

   for (int i=0; i<10; i++)
      testArray[i] = (double)rand()/RAND_MAX*2.0-1.0;//float in range -1 to 1

   memcpy(precord->vala, testArray, 10*sizeof(double));

   if (mySubDebug)
       printf("Record %s called myAsubProcess(%p): ta10=%f\n",
              precord->name, (void*) precord, testArray[9] );
   return 0;
}

===========IOC B==============

record(aSub,"test:RX") {
      field(SNAM, "receiver")
      field(FTA, "DOUBLE")
      field(FTVA, "DOUBLE")
      field(NOA, "10")
      field(NOVA, "10")
      field(INPA, "test:TX.VALA CPP NMS")
}

long receiver(aSubRecord *prec)
{
       double sum=0.0, *a;

       a = (double *)prec->a;

       /*sum goes to output valb*/
       for(int i=0; i<prec->noa; i++)
               sum += a[i];
       * (double *) prec->valb = sum;

       /*copy input A to output VALA*/
       memcpy(prec->vala, (double *)prec->a, 10 * sizeof(double));

       //printf("success: %f\n", sum);

       return 0;
}

On Thu, Jul 27, 2023 at 10:51 AM Ralph Lange via Tech-talk <tech-talk at aps.anl.gov> wrote:

On Thu, 27 Jul 2023 at 21:24, Andrew Johnson via Tech-talk <tech-talk at aps.anl.gov> wrote:

Hi Matt,

On 7/27/23 1:33 PM, Matt Rippa via Tech-talk wrote:

I have 2 aSub records: Tx on IOC  A and Rx on IOC B.

IOC A and B are on different machines on my network.

I want Tx to send an array to Rx over CA (or PVA). Once the data arrives is there a stock method to trigger Rx to process? IIUC, using the CPP attribute in Tx.OUTA will not cause the Rx to process since these records are on different IOC's. I'm using another OUT link in Tx to write to Rx.PROC.

Is that the most efficient way to do this?

The standard and most efficient way would be to have RX.INPA be a CA link to the TX.VALA field with the CPP link flag set, then every time TX updates its VALA field the CA monitor event will update the RX.A array and process that record immediately. If you want to make that processing conditional there are a couple of different ways to do that, but that's a different question for a different email.

Another advantage of this "monitor" style is that the receiving end Rx gets notified when the connection to Tx on IOC A goes down.

Writing data from Tx in "push" style is a fire-and-forget operation: neither side is notified if it fails.

Proper error handling for such setups is yet another question for yet another mail.

Cheers,
~Ralph