Experimental Physics and
Industrial Control System

Carsten Winkler <[email protected]> · Wed, 21 Aug 2013 11:44:29 +0200

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