App coding was of course done in Xcode (Objective C). Communication with the Bluetooth relay strip was done by sending ASCII characters (column three above) in 9600 baud (8/n/1) and listening for responses. For example, sending "B" sets all of the relays to momentary, so that sending further characters such as "e" will trigger a relay (in this case, relay 1 – doors unlock) for one second. Sending "b" returns the current temperature value (in Celcius) from the temperature probe.