[KNX2] Send date+time to KNX produces endless loop

I use OH2 2.3 with this config:

    Thing device NTP  {
        Type datetime-control : date [ ga="11.001:7/0/1" ]
        Type datetime-control : time [ ga="10.001:7/0/0" ]
        Type datetime-control : datetime  [ ga="19.001:7/0/2" ]
    }

DateTime        Datum1                          "Date [%1$tA, %1$td.%1$tm.%1$tY]"                             (All)         { channel="ntp:ntp:local:dateTime,knx:device:bridge:NTP:date,knx:device:bridge:NTP:time" }

After saving the items file I get 20 packages per second on the knx bus.
There are only 20 pkg/s because I have min 50 ms per package, but the buffer is full and it is still sending even after disabling the item.

|#|Zeit|Dienst|Flags |Prio|Quelladresse|Quelle|Zieladresse|Ziel|Rout|Typ|DPT|Info|
|---|---|---|---|---|---|---|---|---|---|---|---|---|
|1582|2018-06-07 00:54:54.027|vom Bus||Low|0.0.2|-|7/0/0|Zeit setzen|4|Schreiben|  10.001 Tageszeit|60 00 00 | Wed 00:00:00|
|1583|2018-06-07 00:54:54.168|vom Bus||Low|0.0.2|-|7/0/0|Zeit setzen|4|Schreiben|  10.001 Tageszeit|60 00 00 | Wed 00:00:00|
|1584|2018-06-07 00:54:54.230|vom Bus||Low|0.0.2|-|7/0/1|Datum setzen|4|Schreiben|  11.001 Datum|06 06 12 | 06.06.2018|
|1585|2018-06-07 00:54:54.277|vom Bus||Low|0.0.2|-|7/0/0|Zeit setzen|4|Schreiben|  10.001 Tageszeit|60 00 00 | Wed 00:00:00|
|1586|2018-06-07 00:54:54.309|vom Bus||Low|0.0.2|-|7/0/0|Zeit setzen|4|Schreiben|  10.001 Tageszeit|60 00 00 | Wed 00:00:00|
|1587|2018-06-07 00:54:54.340|vom Bus||Low|0.0.2|-|7/0/0|Zeit setzen|4|Schreiben|  10.001 Tageszeit|60 00 00 | Wed 00:00:00|
|1588|2018-06-07 00:54:54.387|vom Bus||Low|0.0.2|-|7/0/0|Zeit setzen|4|Schreiben|  10.001 Tageszeit|60 00 00 | Wed 00:00:00|
|1589|2018-06-07 00:54:54.418|vom Bus||Low|0.0.2|-|7/0/0|Zeit setzen|4|Schreiben|  10.001 Tageszeit|60 00 00 | Wed 00:00:00|
|1590|2018-06-07 00:54:54.449|vom Bus||Low|0.0.2|-|7/0/0|Zeit setzen|4|Schreiben|  10.001 Tageszeit|60 00 00 | Wed 00:00:00|
|1591|2018-06-07 00:54:54.496|vom Bus||Low|0.0.2|-|7/0/0|Zeit setzen|4|Schreiben|  10.001 Tageszeit|60 00 00 | Wed 00:00:00|
|1592|2018-06-07 00:54:54.527|vom Bus||Low|0.0.2|-|7/0/0|Zeit setzen|4|Schreiben|  10.001 Tageszeit|60 00 00 | Wed 00:00:00|
|1593|2018-06-07 00:54:54.559|vom Bus||Low|0.0.2|-|7/0/0|Zeit setzen|4|Schreiben|  10.001 Tageszeit|60 00 00 | Wed 00:00:00|
|1594|2018-06-07 00:54:54.637|vom Bus||Low|0.0.2|-|7/0/0|Zeit setzen|4|Schreiben|  10.001 Tageszeit|60 00 00 | Wed 00:00:00|
|1595|2018-06-07 00:54:54.699|vom Bus||Low|0.0.2|-|7/0/0|Zeit setzen|4|Schreiben|  10.001 Tageszeit|60 00 00 | Wed 00:00:00|
|1596|2018-06-07 00:54:54.730|vom Bus||Low|0.0.2|-|7/0/0|Zeit setzen|4|Schreiben|  10.001 Tageszeit|60 00 00 | Wed 00:00:00|
|1597|2018-06-07 00:54:54.777|vom Bus||Low|0.0.2|-|7/0/0|Zeit setzen|4|Schreiben|  10.001 Tageszeit|60 00 00 | Wed 00:00:00|
|1598|2018-06-07 00:54:54.855|vom Bus||Low|0.0.2|-|7/0/0|Zeit setzen|4|Schreiben|  10.001 Tageszeit|60 00 00 | Wed 00:00:00|
|1599|2018-06-07 00:54:54.871|vom Bus||Low|0.0.2|-|7/0/0|Zeit setzen|4|Schreiben|  10.001 Tageszeit|76 36 29 | Wed 22:54:41|
|1600|2018-06-07 00:54:54.949|vom Bus||Low|0.0.2|-|7/0/1|Datum setzen|4|Schreiben|  11.001 Datum|06 06 12 | 06.06.2018|
|1601|2018-06-07 00:54:54.980|vom Bus||Low|0.0.2|-|7/0/0|Zeit setzen|4|Schreiben|  10.001 Tageszeit|60 00 00 | Wed 00:00:00|
23:14:12.307 [INFO ] [ome.event.ThingStatusInfoChangedEvent] - 'knx:device:bridge:NTP' changed from UNINITIALIZED to INITIALIZING
23:14:12.307 [INFO ] [ome.event.ThingStatusInfoChangedEvent] - 'knx:device:bridge:NTP' changed from INITIALIZING to ONLINE
23:14:12.332 [INFO ] [smarthome.event.ItemCommandEvent     ] - Item 'Datum1' received command 2018-06-06T00:00:00.000+0000
23:14:12.335 [INFO ] [smarthome.event.ItemStateChangedEvent] - Datum1 changed from 2018-06-06T23:14:04.785+0000 to 2018-06-06T00:00:00.000+0000
23:14:12.368 [INFO ] [smarthome.event.ItemCommandEvent     ] - Item 'Datum1' received command 1970-01-07T00:00:00.000+0000
23:14:12.369 [WARN ] [knx.internal.client.AbstractKNXClient] - Value '1970-01-07T00:00:00.000+0000' could not be sent to the KNX bus using datapoint 'command DP 7/0/1 'knx:ip:bridge', DPT id 11.001, low priority': 11.001 Date: invalid date: 1970-01-07. Giving up now.
23:14:12.370 [INFO ] [smarthome.event.ItemStateChangedEvent] - Datum1 changed from 2018-06-06T00:00:00.000+0000 to 1970-01-07T00:00:00.000+0000
23:14:12.370 [WARN ] [x.internal.handler.DeviceThingHandler] - An error occurred on channel knx:device:bridge:NTP:date: 11.001 Date: invalid date: 1970-01-07
tuwien.auto.calimero.KNXFormatException: 11.001 Date: invalid date: 1970-01-07
	at tuwien.auto.calimero.dptxlator.DPTXlator.newException(DPTXlator.java:505) ~[224:org.openhab.binding.knx:2.3.0]
	at tuwien.auto.calimero.dptxlator.DPTXlatorDate.toDPT(DPTXlatorDate.java:298) ~[224:org.openhab.binding.knx:2.3.0]
	at tuwien.auto.calimero.dptxlator.DPTXlator.setValue(DPTXlator.java:186) ~[224:org.openhab.binding.knx:2.3.0]
	at tuwien.auto.calimero.process.ProcessCommunicatorImpl.write(ProcessCommunicatorImpl.java:358) ~[224:org.openhab.binding.knx:2.3.0]
	at org.openhab.binding.knx.internal.client.AbstractKNXClient.sendToKNX(AbstractKNXClient.java:444) ~[224:org.openhab.binding.knx:2.3.0]
	at org.openhab.binding.knx.internal.client.AbstractKNXClient.writeToKNX(AbstractKNXClient.java:410) ~[224:org.openhab.binding.knx:2.3.0]
	at org.openhab.binding.knx.internal.handler.DeviceThingHandler.lambda$6(DeviceThingHandler.java:211) ~[224:org.openhab.binding.knx:2.3.0]
	at org.openhab.binding.knx.internal.handler.DeviceThingHandler.withKNXType(DeviceThingHandler.java:121) [224:org.openhab.binding.knx:2.3.0]
	at org.openhab.binding.knx.internal.handler.DeviceThingHandler.withKNXType(DeviceThingHandler.java:115) [224:org.openhab.binding.knx:2.3.0]
	at org.openhab.binding.knx.internal.handler.DeviceThingHandler.handleCommand(DeviceThingHandler.java:208) [224:org.openhab.binding.knx:2.3.0]
	at sun.reflect.GeneratedMethodAccessor131.invoke(Unknown Source) ~[?:?]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[?:?]
	at org.eclipse.smarthome.core.internal.common.AbstractInvocationHandler.invokeDirect(AbstractInvocationHandler.java:153) [101:org.eclipse.smarthome.core:0.10.0.oh230]
	at org.eclipse.smarthome.core.internal.common.InvocationHandlerSync.invoke(InvocationHandlerSync.java:59) [101:org.eclipse.smarthome.core:0.10.0.oh230]
	at com.sun.proxy.$Proxy127.handleCommand(Unknown Source) [224:org.openhab.binding.knx:2.3.0]
	at org.eclipse.smarthome.core.thing.internal.profiles.ProfileCallbackImpl.handleCommand(ProfileCallbackImpl.java:75) [108:org.eclipse.smarthome.core.thing:0.10.0.oh230]
	at org.eclipse.smarthome.core.thing.internal.profiles.SystemFollowProfile.onStateUpdateFromItem(SystemFollowProfile.java:61) [108:org.eclipse.smarthome.core.thing:0.10.0.oh230]
	at sun.reflect.GeneratedMethodAccessor127.invoke(Unknown Source) ~[?:?]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[?:?]
	at org.eclipse.smarthome.core.internal.common.AbstractInvocationHandler.invokeDirect(AbstractInvocationHandler.java:153) [101:org.eclipse.smarthome.core:0.10.0.oh230]
	at org.eclipse.smarthome.core.internal.common.Invocation.call(Invocation.java:53) [101:org.eclipse.smarthome.core:0.10.0.oh230]
	at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:?]
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:?]
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:?]
	at java.lang.Thread.run(Thread.java:748) [?:?]
Caused by: tuwien.auto.calimero.KNXIllegalArgumentException: year out of range [1990..2089]
	at tuwien.auto.calimero.dptxlator.DPTXlatorDate.set(DPTXlatorDate.java:312) ~[?:?]
	at tuwien.auto.calimero.dptxlator.DPTXlatorDate.toDPT(DPTXlatorDate.java:295) ~[?:?]
	... 25 more
23:14:12.371 [INFO ] [smarthome.event.ItemStateChangedEvent] - Datum1 changed from 1970-01-07T00:00:00.000+0000 to 2018-06-06T23:14:12.370+0000
23:14:12.399 [INFO ] [smarthome.event.ItemStateChangedEvent] - Datum1 changed from 2018-06-06T23:14:12.370+0000 to 2018-06-06T23:14:12.402+0000
23:14:12.403 [INFO ] [smarthome.event.ItemCommandEvent     ] - Item 'Datum1' received command 2018-06-06T00:00:00.000+0000
23:14:12.405 [INFO ] [smarthome.event.ItemStateChangedEvent] - Datum1 changed from 2018-06-06T23:14:12.402+0000 to 2018-06-06T00:00:00.000+0000
23:14:12.431 [INFO ] [smarthome.event.ItemStateChangedEvent] - Datum1 changed from 2018-06-06T00:00:00.000+0000 to 2018-06-06T23:14:12.436+0000
23:14:12.441 [INFO ] [smarthome.event.ItemCommandEvent     ] - Item 'Datum1' received command 1970-01-07T23:13:54.000+0000
23:14:12.445 [INFO ] [smarthome.event.ItemStateChangedEvent] - Datum1 changed from 2018-06-06T23:14:12.436+0000 to 1970-01-07T23:13:54.000+0000
23:14:12.446 [WARN ] [knx.internal.client.AbstractKNXClient] - Value '1970-01-07T23:13:54.000+0000' could not be sent to the KNX bus using datapoint 'command DP 7/0/1 'knx:ip:bridge', DPT id 11.001, low priority': 11.001 Date: invalid date: 1970-01-07. Giving up now.
23:14:12.447 [WARN ] [x.internal.handler.DeviceThingHandler] - An error occurred on channel knx:device:bridge:NTP:date: 11.001 Date: invalid date: 1970-01-07
tuwien.auto.calimero.KNXFormatException: 11.001 Date: invalid date: 1970-01-07
	at tuwien.auto.calimero.dptxlator.DPTXlator.newException(DPTXlator.java:505) ~[224:org.openhab.binding.knx:2.3.0]
	at tuwien.auto.calimero.dptxlator.DPTXlatorDate.toDPT(DPTXlatorDate.java:298) ~[224:org.openhab.binding.knx:2.3.0]
	at tuwien.auto.calimero.dptxlator.DPTXlator.setValue(DPTXlator.java:186) ~[224:org.openhab.binding.knx:2.3.0]
	at tuwien.auto.calimero.process.ProcessCommunicatorImpl.write(ProcessCommunicatorImpl.java:358) ~[224:org.openhab.binding.knx:2.3.0]
	at org.openhab.binding.knx.internal.client.AbstractKNXClient.sendToKNX(AbstractKNXClient.java:444) ~[224:org.openhab.binding.knx:2.3.0]
	at org.openhab.binding.knx.internal.client.AbstractKNXClient.writeToKNX(AbstractKNXClient.java:410) ~[224:org.openhab.binding.knx:2.3.0]
	at org.openhab.binding.knx.internal.handler.DeviceThingHandler.lambda$6(DeviceThingHandler.java:211) ~[224:org.openhab.binding.knx:2.3.0]
	at org.openhab.binding.knx.internal.handler.DeviceThingHandler.withKNXType(DeviceThingHandler.java:121) [224:org.openhab.binding.knx:2.3.0]
	at org.openhab.binding.knx.internal.handler.DeviceThingHandler.withKNXType(DeviceThingHandler.java:115) [224:org.openhab.binding.knx:2.3.0]
	at org.openhab.binding.knx.internal.handler.DeviceThingHandler.handleCommand(DeviceThingHandler.java:208) [224:org.openhab.binding.knx:2.3.0]
	at sun.reflect.GeneratedMethodAccessor131.invoke(Unknown Source) ~[?:?]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[?:?]
	at org.eclipse.smarthome.core.internal.common.AbstractInvocationHandler.invokeDirect(AbstractInvocationHandler.java:153) [101:org.eclipse.smarthome.core:0.10.0.oh230]
	at org.eclipse.smarthome.core.internal.common.InvocationHandlerSync.invoke(InvocationHandlerSync.java:59) [101:org.eclipse.smarthome.core:0.10.0.oh230]
	at com.sun.proxy.$Proxy127.handleCommand(Unknown Source) [224:org.openhab.binding.knx:2.3.0]
	at org.eclipse.smarthome.core.thing.internal.profiles.ProfileCallbackImpl.handleCommand(ProfileCallbackImpl.java:75) [108:org.eclipse.smarthome.core.thing:0.10.0.oh230]
	at org.eclipse.smarthome.core.thing.internal.profiles.SystemFollowProfile.onStateUpdateFromItem(SystemFollowProfile.java:61) [108:org.eclipse.smarthome.core.thing:0.10.0.oh230]
	at sun.reflect.GeneratedMethodAccessor127.invoke(Unknown Source) ~[?:?]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[?:?]
	at org.eclipse.smarthome.core.internal.common.AbstractInvocationHandler.invokeDirect(AbstractInvocationHandler.java:153) [101:org.eclipse.smarthome.core:0.10.0.oh230]
	at org.eclipse.smarthome.core.internal.common.Invocation.call(Invocation.java:53) [101:org.eclipse.smarthome.core:0.10.0.oh230]
	at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:?]
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:?]
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:?]
	at java.lang.Thread.run(Thread.java:748) [?:?]
Caused by: tuwien.auto.calimero.KNXIllegalArgumentException: year out of range [1990..2089]
	at tuwien.auto.calimero.dptxlator.DPTXlatorDate.set(DPTXlatorDate.java:312) ~[?:?]
	at tuwien.auto.calimero.dptxlator.DPTXlatorDate.toDPT(DPTXlatorDate.java:295) ~[?:?]
	... 25 more
23:14:12.476 [INFO ] [smarthome.event.ItemCommandEvent     ] - Item 'Datum1' received command 1970-01-07T23:13:48.000+0000
23:14:12.481 [INFO ] [smarthome.event.ItemStateChangedEvent] - Datum1 changed from 1970-01-07T23:13:54.000+0000 to 2018-06-06T23:14:12.478+0000
23:14:12.482 [INFO ] [smarthome.event.ItemStateChangedEvent] - Datum1 changed from 2018-06-06T23:14:12.478+0000 to 1970-01-07T23:13:48.000+0000
23:14:12.484 [WARN ] [knx.internal.client.AbstractKNXClient] - Value '1970-01-07T23:13:48.000+0000' could not be sent to the KNX bus using datapoint 'command DP 7/0/1 'knx:ip:bridge', DPT id 11.001, low priority': 11.001 Date: invalid date: 1970-01-07. Giving up now.
23:14:12.484 [WARN ] [x.internal.handler.DeviceThingHandler] - An error occurred on channel knx:device:bridge:NTP:date: 11.001 Date: invalid date: 1970-01-07
tuwien.auto.calimero.KNXFormatException: 11.001 Date: invalid date: 1970-01-07
	at tuwien.auto.calimero.dptxlator.DPTXlator.newException(DPTXlator.java:505) ~[224:org.openhab.binding.knx:2.3.0]
	at tuwien.auto.calimero.dptxlator.DPTXlatorDate.toDPT(DPTXlatorDate.java:298) ~[224:org.openhab.binding.knx:2.3.0]
	at tuwien.auto.calimero.dptxlator.DPTXlator.setValue(DPTXlator.java:186) ~[224:org.openhab.binding.knx:2.3.0]
	at tuwien.auto.calimero.process.ProcessCommunicatorImpl.write(ProcessCommunicatorImpl.java:358) ~[224:org.openhab.binding.knx:2.3.0]
	at org.openhab.binding.knx.internal.client.AbstractKNXClient.sendToKNX(AbstractKNXClient.java:444) ~[224:org.openhab.binding.knx:2.3.0]
	at org.openhab.binding.knx.internal.client.AbstractKNXClient.writeToKNX(AbstractKNXClient.java:410) ~[224:org.openhab.binding.knx:2.3.0]
	at org.openhab.binding.knx.internal.handler.DeviceThingHandler.lambda$6(DeviceThingHandler.java:211) ~[224:org.openhab.binding.knx:2.3.0]
	at org.openhab.binding.knx.internal.handler.DeviceThingHandler.withKNXType(DeviceThingHandler.java:121) [224:org.openhab.binding.knx:2.3.0]
	at org.openhab.binding.knx.internal.handler.DeviceThingHandler.withKNXType(DeviceThingHandler.java:115) [224:org.openhab.binding.knx:2.3.0]
	at org.openhab.binding.knx.internal.handler.DeviceThingHandler.handleCommand(DeviceThingHandler.java:208) [224:org.openhab.binding.knx:2.3.0]
	at sun.reflect.GeneratedMethodAccessor131.invoke(Unknown Source) ~[?:?]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[?:?]
	at org.eclipse.smarthome.core.internal.common.AbstractInvocationHandler.invokeDirect(AbstractInvocationHandler.java:153) [101:org.eclipse.smarthome.core:0.10.0.oh230]
	at org.eclipse.smarthome.core.internal.common.InvocationHandlerSync.invoke(InvocationHandlerSync.java:59) [101:org.eclipse.smarthome.core:0.10.0.oh230]
	at com.sun.proxy.$Proxy127.handleCommand(Unknown Source) [224:org.openhab.binding.knx:2.3.0]
	at org.eclipse.smarthome.core.thing.internal.profiles.ProfileCallbackImpl.handleCommand(ProfileCallbackImpl.java:75) [108:org.eclipse.smarthome.core.thing:0.10.0.oh230]
	at org.eclipse.smarthome.core.thing.internal.profiles.SystemFollowProfile.onStateUpdateFromItem(SystemFollowProfile.java:61) [108:org.eclipse.smarthome.core.thing:0.10.0.oh230]
	at sun.reflect.GeneratedMethodAccessor127.invoke(Unknown Source) ~[?:?]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[?:?]
	at org.eclipse.smarthome.core.internal.common.AbstractInvocationHandler.invokeDirect(AbstractInvocationHandler.java:153) [101:org.eclipse.smarthome.core:0.10.0.oh230]
	at org.eclipse.smarthome.core.internal.common.Invocation.call(Invocation.java:53) [101:org.eclipse.smarthome.core:0.10.0.oh230]
	at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:?]
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:?]
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:?]
	at java.lang.Thread.run(Thread.java:748) [?:?]
Caused by: tuwien.auto.calimero.KNXIllegalArgumentException: year out of range [1990..2089]
	at tuwien.auto.calimero.dptxlator.DPTXlatorDate.set(DPTXlatorDate.java:312) ~[?:?]
	at tuwien.auto.calimero.dptxlator.DPTXlatorDate.toDPT(DPTXlatorDate.java:295) ~[?:?]
	... 25 more
23:14:12.509 [INFO ] [smarthome.event.ItemCommandEvent     ] - Item 'Datum1' received command 2018-06-06T00:00:00.000+0000
23:14:12.511 [INFO ] [smarthome.event.ItemStateChangedEvent] - Datum1 changed from 1970-01-07T23:13:48.000+0000 to 2018-06-06T00:00:00.000+0000
23:14:12.516 [INFO ] [smarthome.event.ItemStateChangedEvent] - Datum1 changed from 2018-06-06T00:00:00.000+0000 to 2018-06-06T23:14:12.515+0000
23:14:12.553 [INFO ] [smarthome.event.ItemStateChangedEvent] - Datum1 changed from 2018-06-06T23:14:12.515+0000 to 2018-06-06T23:14:12.552+0000
23:14:12.579 [INFO ] [smarthome.event.ItemCommandEvent     ] - Item 'Datum1' received command 1970-01-07T23:13:54.000+0000
23:14:12.580 [WARN ] [knx.internal.client.AbstractKNXClient] - Value '1970-01-07T23:13:54.000+0000' could not be sent to the KNX bus using datapoint 'command DP 7/0/1 'knx:ip:bridge', DPT id 11.001, low priority': 11.001 Date: invalid date: 1970-01-07. Giving up now.
23:14:12.581 [INFO ] [smarthome.event.ItemStateChangedEvent] - Datum1 changed from 2018-06-06T23:14:12.552+0000 to 1970-01-07T23:13:54.000+0000
23:14:12.581 [WARN ] [x.internal.handler.DeviceThingHandler] - An error occurred on channel knx:device:bridge:NTP:date: 11.001 Date: invalid date: 1970-01-07
tuwien.auto.calimero.KNXFormatException: 11.001 Date: invalid date: 1970-01-07
	at tuwien.auto.calimero.dptxlator.DPTXlator.newException(DPTXlator.java:505) ~[224:org.openhab.binding.knx:2.3.0]
	at tuwien.auto.calimero.dptxlator.DPTXlatorDate.toDPT(DPTXlatorDate.java:298) ~[224:org.openhab.binding.knx:2.3.0]
	at tuwien.auto.calimero.dptxlator.DPTXlator.setValue(DPTXlator.java:186) ~[224:org.openhab.binding.knx:2.3.0]
	at tuwien.auto.calimero.process.ProcessCommunicatorImpl.write(ProcessCommunicatorImpl.java:358) ~[224:org.openhab.binding.knx:2.3.0]
	at org.openhab.binding.knx.internal.client.AbstractKNXClient.sendToKNX(AbstractKNXClient.java:444) ~[224:org.openhab.binding.knx:2.3.0]
	at org.openhab.binding.knx.internal.client.AbstractKNXClient.writeToKNX(AbstractKNXClient.java:410) ~[224:org.openhab.binding.knx:2.3.0]
	at org.openhab.binding.knx.internal.handler.DeviceThingHandler.lambda$6(DeviceThingHandler.java:211) ~[224:org.openhab.binding.knx:2.3.0]
	at org.openhab.binding.knx.internal.handler.DeviceThingHandler.withKNXType(DeviceThingHandler.java:121) [224:org.openhab.binding.knx:2.3.0]
	at org.openhab.binding.knx.internal.handler.DeviceThingHandler.withKNXType(DeviceThingHandler.java:115) [224:org.openhab.binding.knx:2.3.0]
	at org.openhab.binding.knx.internal.handler.DeviceThingHandler.handleCommand(DeviceThingHandler.java:208) [224:org.openhab.binding.knx:2.3.0]
	at sun.reflect.GeneratedMethodAccessor131.invoke(Unknown Source) ~[?:?]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[?:?]
	at org.eclipse.smarthome.core.internal.common.AbstractInvocationHandler.invokeDirect(AbstractInvocationHandler.java:153) [101:org.eclipse.smarthome.core:0.10.0.oh230]
	at org.eclipse.smarthome.core.internal.common.InvocationHandlerSync.invoke(InvocationHandlerSync.java:59) [101:org.eclipse.smarthome.core:0.10.0.oh230]
	at com.sun.proxy.$Proxy127.handleCommand(Unknown Source) [224:org.openhab.binding.knx:2.3.0]
	at org.eclipse.smarthome.core.thing.internal.profiles.ProfileCallbackImpl.handleCommand(ProfileCallbackImpl.java:75) [108:org.eclipse.smarthome.core.thing:0.10.0.oh230]
	at org.eclipse.smarthome.core.thing.internal.profiles.SystemFollowProfile.onStateUpdateFromItem(SystemFollowProfile.java:61) [108:org.eclipse.smarthome.core.thing:0.10.0.oh230]
	at sun.reflect.GeneratedMethodAccessor127.invoke(Unknown Source) ~[?:?]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[?:?]
	at org.eclipse.smarthome.core.internal.common.AbstractInvocationHandler.invokeDirect(AbstractInvocationHandler.java:153) [101:org.eclipse.smarthome.core:0.10.0.oh230]
	at org.eclipse.smarthome.core.internal.common.Invocation.call(Invocation.java:53) [101:org.eclipse.smarthome.core:0.10.0.oh230]
	at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:?]
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:?]
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:?]
	at java.lang.Thread.run(Thread.java:748) [?:?]
Caused by: tuwien.auto.calimero.KNXIllegalArgumentException: year out of range [1990..2089]
	at tuwien.auto.calimero.dptxlator.DPTXlatorDate.set(DPTXlatorDate.java:312) ~[?:?]
	at tuwien.auto.calimero.dptxlator.DPTXlatorDate.toDPT(DPTXlatorDate.java:295) ~[?:?]
	... 25 more
23:14:12.609 [INFO ] [smarthome.event.ItemStateChangedEvent] - Datum1 changed from 1970-01-07T23:13:54.000+0000 to 2018-06-06T23:14:12.613+0000
23:14:12.617 [INFO ] [smarthome.event.ItemCommandEvent     ] - Item 'Datum1' received command 1970-01-07T00:00:00.000+0000
23:14:12.622 [INFO ] [smarthome.event.ItemStateChangedEvent] - Datum1 changed from 2018-06-06T23:14:12.613+0000 to 1970-01-07T00:00:00.000+0000
23:14:12.624 [WARN ] [knx.internal.client.AbstractKNXClient] - Value '1970-01-07T00:00:00.000+0000' could not be sent to the KNX bus using datapoint 'command DP 7/0/1 'knx:ip:bridge', DPT id 11.001, low priority': 11.001 Date: invalid date: 1970-01-07. Giving up now.
23:14:12.624 [WARN ] [x.internal.handler.DeviceThingHandler] - An error occurred on channel knx:device:bridge:NTP:date: 11.001 Date: invalid date: 1970-01-07
tuwien.auto.calimero.KNXFormatException: 11.001 Date: invalid date: 1970-01-07
	at tuwien.auto.calimero.dptxlator.DPTXlator.newException(DPTXlator.java:505) ~[224:org.openhab.binding.knx:2.3.0]
	at tuwien.auto.calimero.dptxlator.DPTXlatorDate.toDPT(DPTXlatorDate.java:298) ~[224:org.openhab.binding.knx:2.3.0]
	at tuwien.auto.calimero.dptxlator.DPTXlator.setValue(DPTXlator.java:186) ~[224:org.openhab.binding.knx:2.3.0]
	at tuwien.auto.calimero.process.ProcessCommunicatorImpl.write(ProcessCommunicatorImpl.java:358) ~[224:org.openhab.binding.knx:2.3.0]
	at org.openhab.binding.knx.internal.client.AbstractKNXClient.sendToKNX(AbstractKNXClient.java:444) ~[224:org.openhab.binding.knx:2.3.0]
	at org.openhab.binding.knx.internal.client.AbstractKNXClient.writeToKNX(AbstractKNXClient.java:410) ~[224:org.openhab.binding.knx:2.3.0]
	at org.openhab.binding.knx.internal.handler.DeviceThingHandler.lambda$6(DeviceThingHandler.java:211) ~[224:org.openhab.binding.knx:2.3.0]
	at org.openhab.binding.knx.internal.handler.DeviceThingHandler.withKNXType(DeviceThingHandler.java:121) [224:org.openhab.binding.knx:2.3.0]
	at org.openhab.binding.knx.internal.handler.DeviceThingHandler.withKNXType(DeviceThingHandler.java:115) [224:org.openhab.binding.knx:2.3.0]
	at org.openhab.binding.knx.internal.handler.DeviceThingHandler.handleCommand(DeviceThingHandler.java:208) [224:org.openhab.binding.knx:2.3.0]
	at sun.reflect.GeneratedMethodAccessor131.invoke(Unknown Source) ~[?:?]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[?:?]
	at org.eclipse.smarthome.core.internal.common.AbstractInvocationHandler.invokeDirect(AbstractInvocationHandler.java:153) [101:org.eclipse.smarthome.core:0.10.0.oh230]
	at org.eclipse.smarthome.core.internal.common.InvocationHandlerSync.invoke(InvocationHandlerSync.java:59) [101:org.eclipse.smarthome.core:0.10.0.oh230]
	at com.sun.proxy.$Proxy127.handleCommand(Unknown Source) [224:org.openhab.binding.knx:2.3.0]
	at org.eclipse.smarthome.core.thing.internal.profiles.ProfileCallbackImpl.handleCommand(ProfileCallbackImpl.java:75) [108:org.eclipse.smarthome.core.thing:0.10.0.oh230]
	at org.eclipse.smarthome.core.thing.internal.profiles.SystemFollowProfile.onStateUpdateFromItem(SystemFollowProfile.java:61) [108:org.eclipse.smarthome.core.thing:0.10.0.oh230]
	at sun.reflect.GeneratedMethodAccessor127.invoke(Unknown Source) ~[?:?]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[?:?]
	at org.eclipse.smarthome.core.internal.common.AbstractInvocationHandler.invokeDirect(AbstractInvocationHandler.java:153) [101:org.eclipse.smarthome.core:0.10.0.oh230]
	at org.eclipse.smarthome.core.internal.common.Invocation.call(Invocation.java:53) [101:org.eclipse.smarthome.core:0.10.0.oh230]
	at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:?]
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:?]
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:?]
	at java.lang.Thread.run(Thread.java:748) [?:?]
Caused by: tuwien.auto.calimero.KNXIllegalArgumentException: year out of range [1990..2089]
	at tuwien.auto.calimero.dptxlator.DPTXlatorDate.set(DPTXlatorDate.java:312) ~[?:?]
	at tuwien.auto.calimero.dptxlator.DPTXlatorDate.toDPT(DPTXlatorDate.java:295) ~[?:?]
	... 25 more
23:14:12.651 [INFO ] [smarthome.event.ItemStateChangedEvent] - Datum1 changed from 1970-01-07T00:00:00.000+0000 to 2018-06-06T23:14:12.653+0000
23:14:12.653 [INFO ] [smarthome.event.ItemCommandEvent     ] - Item 'Datum1' received command 2018-06-06T00:00:00.000+0000
23:14:12.654 [INFO ] [smarthome.event.ItemStateChangedEvent] - Datum1 changed from 2018-06-06T23:14:12.653+0000 to 2018-06-06T00:00:00.000+0000
23:14:12.680 [INFO ] [smarthome.event.ItemStateChangedEvent] - Datum1 changed from 2018-06-06T00:00:00.000+0000 to 2018-06-06T23:14:12.685+0000
23:14:12.724 [INFO ] [smarthome.event.ItemCommandEvent     ] - Item 'Datum1' received command 1970-01-07T00:00:00.000+0000

You may have stumbled upon a bug… It wouldn’t hurt to open up an issue on https://github.com/openhab/openhab2-addons/issues for the [knx] binding.

I would include also the ntp.things and (complete) knx.things file contents (to be able to fully reproduce the case)