Experimental Physics and
Industrial Control System

"Jeff Hill" <[email protected]> · Wed, 8 Oct 2003 12:41:40 -0600

> 	Where is placed overhead? Before DBR_XXX structure or after N-1
> array?

Just before the payload - the payload includes both the DBR_XXX structure
and the N-1 array.

Jeff

> 
> Andrei.
> 
> -----Original Message-----
> From: Jeff Hill [mailto:[email protected]]
> Sent: Wednesday, October 08, 2003 11:42 AM
> To: Liyu, Andrei; [email protected]
> Subject: RE: CA; data length before TCP level
> 
> 
> Hi Andrei,
> 
> The data payload size for an N element array will be the size of the
> DBR_XXX
> type plus N-1 times the size of the value field in the DBR_XXX type. The
> Channel Access overhead for data payloads less than 64k bytes is 16
> bytes.
> The Channel Access overhead for data payloads greater than 64k bytes is
> 24
> bytes.
> 
> Jeff
> 
> > -----Original Message-----
> > From: Liyu, Andrei [mailto:[email protected]]
> > Sent: Tuesday, October 07, 2003 3:26 PM
> > To: [email protected]
> > Subject: CA; data length before TCP level
> >
> > Hi,
> >        Example.
> >        Client opens CA channel to PV. PV is big array. Client is
> getting
> > data 100, 1000, ... Server does data packet. Data packet consists from
> >       - head of data has timestamps, status, severity and so on
> > 	- array
> > 	- additional data for connection to client computer, to client
> > program, to this channel and so on.
> >
> > We would like to know how we may calculate exact number bytes of data
> > packet before TCP level.
> > Can someone explain data structure for network?
> >
> > Thanks, Andrei.

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System