Return codes jowfs client

Hello Everybody,

I’m still trying to regulate the Floorheating of my House with Openhab. I use
https://www.eservice-online.de/produkte/1-wire-bus/eingang-ausgang-zaehler/85/1-wire-8-fach-schaltmodul-230v-5a?c=119 to switch the Valves, http://www.embeddeddatasystems.com/OW-SERVER-1-Wire-to-Ethernet-Server-Revision-2_p_152.html as Busmasters (3, one for each structural level), DS18B20 to measure the Temperatures and of course owserver (the software from owfs.org) to provide all Devices for Openhab. Openhab.log says too often org.owfs.jowfsclient.OwfsException: Error -2 or org.owfs.jowfsclient.OwfsException: Error -1. Does anyone know what -1 and -2 is?

Best Regards