The VP2 Console has an expansion port that you can plug various data logger modules into an expansion port on the back of the console. The data loggers provide an interface to the outside world; either serial, USB or IP, and provide extra storage capacity. Currently you can get Windows Serial; Windows USB; Mac USB; & an IP logger. The expansion port in the back is actually a simple serial port. It's possible to access this directly, although after the infamous version 3 or "green dot" firmware update it's a bit more convoluted to do so. However that aside, the first two dataloggers are fairly simply devices that just summarise the serial data and pass it on via serial or USB interface. The third one is a bit more complex in that it has the option to automatically upload the data to the Davis WeatherLink servers on the Internet. You can use third party software to connect to the dataloggers eg Weather Display. All the dataloggers will store a certain amount of data as a history which can be accessed by software using the right comms protocols. Helpfully, Davis do publish these protocols so my initial thought was to use these to access the WeatherLink IP with my own software. However when I went looking for the protocols for accessing the WeatherLink IP, it wasn't very clear what was going on. As far as I can make out all the dataloggers essential use the same access mechanism irrespective of the transport layer involved, and that is derived from a serial access mechanism. This isn't too much of a problem for the serial or USB devices where only one device at a time can physically talk to the console at once. But for the WeatherLink IP it does become critical. With an IP based datalogger there's nothing to stop multiple devices from accessing it at the same. Except in the case of the WeatherLink IP, as far as I can make out, it's using the original serial based protocols and simply routing them over IP. This means only one device can access the logger at one time.
Davis Vantage Pro 2 Serial Protocol
If you can live with a used one, you can find these for sale on Ebay from time to time. Davis also makes a USB version of the module, which is the exact same thing but includes an FTDI usb to serial chip built-in. It is more expensive than the regular serial version and runs at the same 19200 baud rate, so really no advantages and a waste of money. 2ff7e9595c
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