We´ve checked the connections between the touch panel and PLC and the cable and connectors are ok. The "comm" light on the PLC is flashing when the machine is turned on (does this tell you something?)
Regarding the message displayed "Connecting to host", perhaps you should know that the battery drained while the machine was off (weekend). According to the manual, it must be replaced within 5 minutes "to protect the contents of the memory". As this didn´t happen, could this be the cause of the message displayed?