I would like to hire an Android Developer

Project: Multipurpose user interface for smartphone or webbased control of embedded industrial control modules via RF using the modbus RTU protocol (hex) Eample #1 Automatic tyre inflater: The interface would be able to read and display the setpoint , the current tyre pressure and control the unit with 4 buttons, namely Up Down Start and Reset Example #2 Control Ventilation as part of a building management system Same basic requirement, read and display some values like battery voltage or current and have appropriate buttons to open, close vents, monitor number of operations ( maintenance ) and over-ride existing input signals. Modbus: The smartphone or webpage would be the master, the devices are the slaves RTU's. Only some commands of the modbus protocol will be implement. Typically read or write multiple registers or single bits like relay status. The Chipkin Modbus for field technicians is a very good reference document. The remote devices act like PLC's and will respond with the appropriate error code, should a message be incorrectly formulated, be out of range or have the wrong CRC. Not more than 64 words of 16 bits would be required for the modbus database. There are two ( perhaps more ) options. It depends what is more cost effective. One way is to have a dedicated app for each product, mostly due to screen layout issues ore have a more general purpose approach, whereby the app is broken down in to functional blocks that just get dragged on to the screen and the memory location, naming, and control functions assigned. Typically the control devices are not connected to the web. You have to be in close proximity with the smart phone which could then act as a modem. In addition, users may have permission only for certain data.