EUROtronic Comet Z logs Timeout every 30 Minutes

I have successfully include two Comet Z Thermostats in openHAB2 with the Z-Wave Binding. I use the Aeotec USB Z-Stick ZW090-C. I can set temperature, mode and i get the temperature. So it seems the Comet Z is working well. But ever 30 Minutes I have entries in the openhab.log. I attached a part of the openhab.log. NODE 3 and NODE 5 are the Comet Z Devices.

2017-03-01 14:30:04.056 [ERROR] [ocol.ZWaveController$ZWaveSendThread] - NODE 3: Timeout while sending message. Requeueing - 2 attempts left!
2017-03-01 14:31:06.905 [ERROR] [ocol.ZWaveController$ZWaveSendThread] - NODE 3: Timeout while sending message. Requeueing - 1 attempts left!
2017-03-01 14:32:09.425 [ERROR] [ocol.ZWaveController$ZWaveSendThread] - NODE 3: Timeout while sending message. Requeueing - 0 attempts left!
2017-03-01 14:33:11.943 [WARN ] [ocol.ZWaveController$ZWaveSendThread] - NODE 3: Too many retries. Discarding message: Message: class=SendData[0x13], type=Request[0x00], priority=Immediate, dest=3, callback=98, payload=03 03 43 02 07 
2017-03-01 14:42:30.180 [ERROR] [ocol.ZWaveController$ZWaveSendThread] - NODE 5: Timeout while sending message. Requeueing - 2 attempts left!
2017-03-01 14:43:32.715 [ERROR] [ocol.ZWaveController$ZWaveSendThread] - NODE 5: Timeout while sending message. Requeueing - 1 attempts left!
2017-03-01 14:44:35.183 [ERROR] [ocol.ZWaveController$ZWaveSendThread] - NODE 5: Timeout while sending message. Requeueing - 0 attempts left!
2017-03-01 14:45:37.654 [WARN ] [ocol.ZWaveController$ZWaveSendThread] - NODE 5: Too many retries. Discarding message: Message: class=SendData[0x13], type=Request[0x00], priority=Immediate, dest=5, callback=139, payload=05 03 43 02 07 
2017-03-01 14:59:40.823 [ERROR] [ocol.ZWaveController$ZWaveSendThread] - NODE 3: Timeout while sending message. Requeueing - 2 attempts left!
2017-03-01 15:00:43.654 [ERROR] [ocol.ZWaveController$ZWaveSendThread] - NODE 3: Timeout while sending message. Requeueing - 1 attempts left!
2017-03-01 15:01:46.147 [ERROR] [ocol.ZWaveController$ZWaveSendThread] - NODE 3: Timeout while sending message. Requeueing - 0 attempts left!
2017-03-01 15:02:48.632 [WARN ] [ocol.ZWaveController$ZWaveSendThread] - NODE 3: Too many retries. Discarding message: Message: class=SendData[0x13], type=Request[0x00], priority=Immediate, dest=3, callback=201, payload=03 03 43 02 07 
2017-03-01 15:12:05.923 [ERROR] [ocol.ZWaveController$ZWaveSendThread] - NODE 5: Timeout while sending message. Requeueing - 2 attempts left!
2017-03-01 15:13:08.468 [ERROR] [ocol.ZWaveController$ZWaveSendThread] - NODE 5: Timeout while sending message. Requeueing - 1 attempts left!
2017-03-01 15:14:10.943 [ERROR] [ocol.ZWaveController$ZWaveSendThread] - NODE 5: Timeout while sending message. Requeueing - 0 attempts left!
2017-03-01 15:15:13.422 [WARN ] [ocol.ZWaveController$ZWaveSendThread] - NODE 5: Too many retries. Discarding message: Message: class=SendData[0x13], type=Request[0x00], priority=Immediate, dest=5, callback=242, payload=05 03 43 02 07 
2017-03-01 15:30:18.225 [ERROR] [ocol.ZWaveController$ZWaveSendThread] - NODE 3: Timeout while sending message. Requeueing - 2 attempts left!
2017-03-01 15:31:21.041 [ERROR] [ocol.ZWaveController$ZWaveSendThread] - NODE 3: Timeout while sending message. Requeueing - 1 attempts left!
2017-03-01 15:32:23.515 [ERROR] [ocol.ZWaveController$ZWaveSendThread] - NODE 3: Timeout while sending message. Requeueing - 0 attempts left!
2017-03-01 15:33:25.991 [WARN ] [ocol.ZWaveController$ZWaveSendThread] - NODE 3: Too many retries. Discarding message: Message: class=SendData[0x13], type=Request[0x00], priority=Immediate, dest=3, callback=51, payload=03 03 43 02 07 
2017-03-01 15:42:42.438 [ERROR] [ocol.ZWaveController$ZWaveSendThread] - NODE 5: Timeout while sending message. Requeueing - 2 attempts left!
2017-03-01 15:43:44.978 [ERROR] [ocol.ZWaveController$ZWaveSendThread] - NODE 5: Timeout while sending message. Requeueing - 1 attempts left!
2017-03-01 15:44:47.446 [ERROR] [ocol.ZWaveController$ZWaveSendThread] - NODE 5: Timeout while sending message. Requeueing - 0 attempts left!
2017-03-01 15:45:49.915 [WARN ] [ocol.ZWaveController$ZWaveSendThread] - NODE 5: Too many retries. Discarding message: Message: class=SendData[0x13], type=Request[0x00], priority=Immediate, dest=5, callback=92, payload=05 03 43 02 07 

In the Paper UI the Comet Z has these Properties:
zwave_class_basic ROUTING_SLAVE
zwave_class_generic THERMOSTAT
zwave_frequent false
zwave_neighbours
zwave_version 0.5
zwave_listening false
zwave_deviceid 1
zwave_nodeid 5
zwave_routing true
zwave_wakeup_time 2017-03-01T15:20:26Z
zwave_beaming true
zwave_class_specific THERMOSTAT_GENERAL_V2
zwave_manufacturer 328
zwave_devicetype 2

What can cause the problem and where can I look to find out what the problem is.