Experimental Physics and
Industrial Control System

"Kasemir, Kay" <[email protected]> · Wed, 21 Aug 2013 09:24:06 -0400

Looks like you are asking for a DBRType.DOUBLE in the addMonitor, but the actual value (string) cannot be converted.
Ask for the 'native' value by adding a connection listener, then inside the connection listener do the addMonitor with the native data type.

-Kay

On Aug 21, 2013, at 5:44 AM, Carsten Winkler <[email protected]> wrote:

> Hi all,
> 
> it seems CAJ can't handle DBR_String.
> If you request the value of a stringout or stringin EPICS variable you
> always get a NullPointerException.
> Also if you ask for the DESC field of any PV you'll get same error.
> If you dig deeper you see the DBRType of the created channel is
> UNKNOWN.  Where comes this type come from? You find the problem in
> "com.cosylab.epics.caj.CAJChannel.connectionCompleted(int sid, short
> typeCode, int elementCount) ". This function gets the parameter
> "typeCode" and the value of this parameter is "UNKNOWN" instead of
> "STRING". But who sets the "typeCode"? The "typeCode" will be extracted
> from the CA response header (AbstractCAResponseHandler) and here ends my
> trace.
> Did I miss something? Please check my source code and tell me what to do
> to get strings.
> 
> public class CAJBugTest {
>     public static void main(String[] args) throws Exception {
>         JCALibrary jca = JCALibrary.getInstance();
>         Context ctxt = jca.createContext(JCALibrary.CHANNEL_ACCESS_JAVA);
>         Channel ch = ctxt.createChannel("INFOCL:scale.DESC");
>         ch.addMonitor(DBRType.DOUBLE, 1, Monitor.VALUE, new
> MonitorListener() {
>             @Override
>             public void monitorChanged(MonitorEvent ev) {
>                 System.out.println(ev.getDBR().getValue());
>             }
>         });
>         ctxt.flushIO();
>         Thread.sleep(5000);
>         ch.destroy();
>         ctxt.destroy();
>     }
> }
> 
> Cheers,
> Carsten
> 
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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System