Marcus Gylling MC S- 2004:23, pp. 36. TEK/avd. för programvaruteknik, 2004.
The controlling unit in building management system automation is a PLC. Every device in an
installation is connected to the PLC. When a user wants to interact with a system an operator
terminal, which is attached to a cabinet where the PLC is installed, is used. With this solution the
user needs to be in front of the cabinet to interact with the system. Alarms do not get the user’s
attention until the user checks the operator terminal.
Using a solution where the communication with the PLC is done with a wireless interface would
mean that the user interact with a system from a wider area. The solution should have the same
functionality as today with the extension that the PLC should be able to contact the user if
something is wrong in the installation.
A PDA is used as a replacement for the operator terminal. This PDA uses two different techniques
to communicate with the PLC. Bluetooth is used when the user is in the building and interacts
with the system in a similar way to the operator terminals. GSM is used when the PLC needs to
get the users attention by sending out alarms. With this solution the PDA can be used for several
installations and thereby decrease cost.
The project has turned out to be a success. The application that has been developed has improved
a user’s interaction with a PLC.