Here is pages from the Ops Manual for the Vent:
Philips Respironics V200 User .pdf
Chapter 13 (Pages 13-78 to 13-81)
The Trending Not Available message indicates a problem with Trending option data storage
This message may appear if:
•the PCMCIA card installed for the Trending option is removed,
•the PCMCIA card includes unrecognizable or corrupted files, or •the PCMCIA card does not contain enough memory.
•the internal clock setting was moved back by more than 1.25 hours and trending data was not erased.Contact Respironics Technical Support for more information.
WARNING:The cover plate for the PCMCIA slot at the back of the ventilator must be replaced after the adapter and card are installed. This is to protect the ventilator.
CAUTION:The PCMCIA card should only be removed by trained service personnel once power to the ventilator is off.
Data collection and display. The system collects numeric data every 20 seconds.
Alarms are considered active if they occurred at any time during the previous 20-second interval.
If the selected time scale is 2 hours, each data point on a waveform represents 20 seconds.
As the scale is increased, each data point represents a longer interval.Data is periodically refreshed if there is no user interaction.Display time-outsThe Trending screen automatically reverts to the Monitor screen if 15 minutes elapse without user interaction.
Pop-up windows are cleared from the display if 2 minutes elapse without user interaction, and any pending changes are cancelled.
Table 13-12: Trending Data Specifications (Sheet 1 of 4) Page 13-81.
If you did all of that, then need to check interconnecting cables inside the vent to the front panel. It could also be the front panel or its interface.