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<== Date ==> <== Thread ==>
Subject: Re: How to access bigstring using channel access
From: Deeptarka Das/TVM/TCS <[email protected]>
To: Ralph Lange <[email protected]>
Cc: EPICS Tech-Talk <[email protected]>
Date: Fri, 16 Jan 2015 11:03:00 +0530 (IST)

Hi Ralph,

 

Thanks for the prompt reply. However, just let me add, that appending $ at the end, represents the string in the form of an array containing ASCII values of the original characters in the string. I had to add the -S modifier to get what I desired.

 

caget mybigstring.VAL$   -->   array of char (max EPICS_CA_MAX_ARRAY_BYTES - 1)
caget -S mybigstring.VAL$   --> the full length string

 

Thanks and Regards,

Deeptarka

From: "Ralph Lange" <[email protected]>
To: "EPICS Tech-Talk" <[email protected]>
Sent: Thursday, January 15, 2015 7:03:35 PM
Subject: Re: How to access bigstring using channel access

Hi Deeptarka,

Try appending a dollar sign to the PV name when connecting through Channel Access. The IOC takes that as a hint to represent a string field as an array of char, so that CA can transfer more chars than the fixed-size string would allow.

    caget mybigstring.VAL    -->   string (fix 39 chars)
    caget mybigstring.VAL$   -->   array of char (max EPICS_CA_MAX_ARRAY_BYTES - 1)

HTH,
~Ralph


On 15/01/2015 07:56, Deeptarka Das/TVM/TCS wrote:

Hi all,

 

I would like to know if there is some way by which channel access can be used to put and get strings of size larger than 40. I do not wish to use waveform record nor do i wish to use pvaSrv to access PVs using pvAccess. Rather I would like to use the bigstring recordtype of EPICS V4 with channel access. Is there any way it is possible by maybe changing something in epics base?

--
Thanks and Regards,
Deeptarka Das
Mailto: [email protected]




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