Just made two changes to the server code: The first time a vehicle fails to authenticate (wrong server password), the Apps for that vehicle will now be sent a push notification telling them about the problem (along with the IP address of the vehicle). If the vehicle subsequently managed to authenticate correctly, the apps will get another notification telling them that. Hopefully this will help with setup in cases where the server password is incorrect. I've added a second method to submit vehicle history - the 'h' message. This is the same as 'H', but is prefixed with two extra fields - an acknowledgement ID and a time difference (in seconds). When the server receives an 'h' message, it replies with an 'h' message of its own, containing just the acknowledgement ID. The time difference is used to move the historical data timestamp back the given number of seconds. This allows the vehicles to send in historical data delayed by N seconds (for example, if the link is down and they can't immediately submit). It also allows the vehicles to get back an acknowledgement that the data has actually been recorded successfully. The new server code is already live. I'll commit to github with the ACC stuff I'm currently finalising, as soon as a I can (but maybe a few more days until its ready). Regards, Mark.