Re: Long string PV access in CA client.

["Kasemir, Kay via Tech-talk" <tech-talk at aps.anl.gov>]

You need to use “pvname.VAL$”. The IOC will then use char[] for the value instead of the ‘string’.

For type and count, you can use the values that you get in the connect callback.

Should be a char[] type with size based on the text length, so the type to read needs to be one of the DBR…CHAR types with that count.

 

 

From: Tech-talk <tech-talk-bounces at aps.anl.gov> on behalf of Li, Ji via Tech-talk <tech-talk at aps.anl.gov>
Date: Friday, August 9, 2024 at 2:51 PM
To: tech-talk at aps.anl.gov <tech-talk at aps.anl.gov>
Subject: [EXTERNAL] Long string PV access in CA client.

Hi,

 

I have a CA client that monitors several PVs through subscription (ca_create_subscription), gets values by copying from corresponding eha.dbr fields, and puts values to some PVs. It works well with all PVs except for long string ones, as it behaves like caget command withou -S option, i.e., it can only access the first 40 characters of the PV values. For it to work properly with long strings, how do I:

• specify a PV. Should I use pvname or pvname.VAL$? 

• subscribe. What type and count value should be used for the function call?

•  

• get. Is the returned value stored in eha.dbr?

• put. How to write a long string to a (lsi) PV?

 

Best,

-Ji