PV¶

PV instances belong to a single widget. The PV Name identifies what data it represents, and may come from various different data sources.

getName()

Returns the PV Name.

getValue()

Returns the current value of this PV.

setValue( value )

Write a value to this PV. This method returns immediately.

setValue( value, timeout )

Write a value to this PV and block until either the write was successful, or the timeout (in milliseconds) was reached.

Returns true if the write was successful.

start()

Connect and start listening to updates. It is not allowed to start an already started PV.

stop()

Disconnect a PV. Its listeners are preserved for a potential future restart.

addListener( listener )

Add an IPVListener implementation for receiving updates. Example:

var IPVListener = Java.type("org.yamcs.studio.data.IPVListener");
myPV.addListener(new IPVListener({
    valueChanged: function(pv) {
        ConsoleUtil.writeInfo("An update: " + PVUtil.getString(pv));
    }
}));

Note

In most circumstances it would be preferrable to add the PV of interest as a trigger to the Input PVs of a particular script, so that value updates can more simply be accessed from the global pvs array.

removeListener( listener )

Stop an IPVListener implementation from receiving updates.

isConnected()

Returns true if this PV is currently connected. What this means depends on the underlying datasource. For example, if it concerns a Yamcs parameter, connected means that the WebSocket subscription is up and running.

isWriteAllowed()

Returns true if this PV may be used in control widgets.

PVs for Yamcs parameters accept all writes, and leave the finally decision to Yamcs itself.