A fieldbus controller, comprising: a plurality of I/O modules connectable to a controlled device; a processor and memory; a wireless communication interface operatively coupled to the processor and configured to provide wireless connectivity between the fieldbus controller and a portable hand-held electronic device for an active time period; and computer-executable instructions stored in the memory and executable by the processor, wherein the computer-executable instructions comprise logic which when executed by the processor provides, via the wireless communication interface and using the wireless connectivity, a user interface to the portable hand-held electronic device for operating the fieldbus controller, wherein the user interface includes: a configuration interface for configuring an operating mode of the plurality of I/O modules, wherein the configuration interface includes an interface for configuring the plurality of I/O modules by defining a type of each of the plurality of I/O modules, and wherein defining the type of each of the plurality of I/O modules includes selecting the type of I/O module to be at least one of a PNP module or an NPN module; a monitor interface for reading status information from the plurality of I/O modules; and a control interface for controlling a state of the plurality of I/O modules, the state of the plurality of I/O modules affecting a state of the controlled device. a plurality of I/O modules connectable to a controlled device; a processor and memory; a wireless communication interface operatively coupled to the processor and configured to provide wireless connectivity between the fieldbus controller and a portable hand-held electronic device for an active time period; and computer-executable instructions stored in the memory and executable by the processor, wherein the computer-executable instructions comprise logic which when executed by the processor provides, via the wireless communication interface and using the wireless connectivity, a user interface to the portable hand-held electronic device for operating the fieldbus controller, wherein the user interface includes: a configuration interface for configuring an operating mode of the plurality of I/O modules, wherein the configuration interface includes an interface for configuring the plurality of I/O modules by defining a type of each of the plurality of I/O modules, and wherein defining the type of each of the plurality of I/O modules includes selecting the type of I/O module to be at least one of a PNP module or an NPN module; a monitor interface for reading status information from the plurality of I/O modules; and a control interface for controlling a state of the plurality of I/O modules, the state of the plurality of I/O modules affecting a state of the controlled device. a configuration interface for configuring an operating mode of the plurality of I/O modules, wherein the configuration interface includes an interface for configuring the plurality of I/O modules by defining a type of each of the plurality of I/O modules, and wherein defining the type of each of the plurality of I/O modules includes selecting the type of I/O module to be at least one of a PNP module or an NPN module; a monitor interface for reading status information from the plurality of I/O modules; and a control interface for controlling a state of the plurality of I/O modules, the state of the plurality of I/O modules affecting a state of the controlled device.