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<== Date ==> <== Thread ==>

Subject: RE: CA_PROTO_READ_NOTIFY Response
From: "Hill, Jeffrey O" <johill@lanl.gov>
To: "graham.cox@stfc.ac.uk" <graham.cox@stfc.ac.uk>, "tech-talk@aps.anl.gov" <tech-talk@aps.anl.gov>
Date: Wed, 2 May 2012 15:04:46 +0000

Ø  According to the Channel Access protocol specification from the Cosylab website,

Ø  parameter 1 of the header of a CA_PROTO_READ_NOTIFY response contains the

Ø  channel SID (the same as the request header received).

 

typedef struct ca_hdr {

    ca_uint16_t m_cmmd;         /* operation to be performed */

    ca_uint16_t m_postsize;     /* size of payload */

    ca_uint16_t m_dataType;     /* operation data type */

    ca_uint16_t m_count;        /* operation data count */

    ca_uint32_t m_cid;          /* channel identifier */

    ca_uint32_t m_available;    /* protocol stub dependent */

} caHdr;

 

The m_cid field in the CA_PROTO_READ_NOTIFY response message header

communicates the CA status (see caerr.h) of the request, as it was executed in the

server, with this request type.

 

Jeff

 

From: tech-talk-bounces@aps.anl.gov [mailto:tech-talk-bounces@aps.anl.gov] On Behalf Of graham.cox@stfc.ac.uk
Sent: Wednesday, May 02, 2012 5:13 AM
To: tech-talk@aps.anl.gov
Subject: CA_PROTO_READ_NOTIFY Response

 

All,

 

According to the Channel Access protocol specification from the Cosylab website, parameter 1 of the header of a CA_PROTO_READ_NOTIFY response contains the channel SID (the same as the request header received).

 

Is this correct?  Monitoring network traffic from a 3.14.12 win32-x86 soft IOC, this value always appears to a fixed value of 1, no matter what the serverID, or clientID of the channel.  Returning anything other than 1 also appears to break correct functioning of a caget.

 

Thanks,

 

Graham

 

Header

Field

Value

Description

Command

15

Command identifier for CA_PROTO_READ_NOTIFY.

Payload size

Size of payload

Size of DBR formatted data in payload.

Data type

DBR type

Payload format.

Data count

>= 0

Payload element count.

SID

Same as request

SID of the channel.

IOID

Same as request

IOID of this operation.

 

 

--
Scanned by iCritical.

 


References:
CA_PROTO_READ_NOTIFY Response graham.cox

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