Is the issues 470 open?
I get WARN
2015-09-30 12:59:58.937 [WARN ] [ipse.jetty.client.HttpExchange] - EXPIRED FritzahaContentExchange@1a1822d=GET//192.168.0.254:80/net/home_auto_query.lua?xhr=1&command=MultiMeterState&id=17&sid=1377c57e5a6b8e0c#WAITING(3964ms)->EXPIRED(0ms)sent=3964ms
I set the Timeout in the openhab.cfg to 3 minutes.
Dokumentation http://avm.de/fileadmin/user_upload/Global/Service/Schnittstellen/AHA-HTTP-Interface.pdf
Test im Browser fritz.box/net/home_auto_query.lua?xhr=1&command=MultiMeterState&id=16&sid=5d7ff1075d5d1788 get the right answer:
{
“MM_Value_Power” : “5636” ,“MM_Value_Volt” : “232164” ,“MM_Value_Amp” : “4590” ,“Value_Valid” : “2” ,“CurrentDateInSec” : “1443617009” ,“DeviceID” : “16” ,“tabType” : “” ,“DeviceConnectState” : “2” ,“RequestResult” : “1”
}