public CEMILData request(final KNXAddress dst, final Configuration c)
	{
		final Cache cache = c.getCache();
		if (cache == null || !(dst instanceof GroupAddress))
			return null;
		final LDataObject o = (LDataObject) cache.get(dst);
		if (o == null)
			return null;
		// check if there is an expiration timeout for a state based value
		final Datapoint dp;
		final DatapointModel m = c.getDatapointModel();
		if (m != null && (dp = m.get((GroupAddress) dst)) != null && dp.isStateBased()) {
			final int t = ((StateDP) dp).getExpirationTimeout() * 1000;
			if (t != 0 && System.currentTimeMillis() > o.getTimestamp() + t)
				return null;
		}
		return o.getFrame();
	}