Abstract: A bidirectional serial communication interface comprising a slave powered by a master connected to the slave via a signal line and a return line is disclosed. The master includes a master switch inserted in a line connecting a supply voltage to the signal line and a transceiver transmitting binary signals by opening and closing the master switch and receiving binary signals whilst the master switch is open. The slave includes an energy storage charged via the signal line and providing an internal power supply; a pull-up switch inserted in a line connecting the signal line to the internal power supply; a pull-down switch inserted in a line connecting the signal line to the return line; and a transceiver transmitting binary signals by opening and closing the pull-up and the pull-down switch whilst the master switch is open and receiving binary signals whilst the pull-up and the pull-down switch are open.

Abstract: A module for asynchronous differential serial communication on a bus is disclosed. The module is connectable to the bus in a first connecting mode, wherein a non-inverting terminal of the module is connected to a non-inverted bus signal line and an inverting terminal is connected to an inverted bus signal line, and a second connecting mode given by an inverse of the first connecting mode. The module includes a detector determining the connecting mode based on the binary state of a start bit of a reception signal provided by a transceiver of the module based on a received communication signal and a binary state of a first bit of a reference signal corresponding to a voltage difference between the voltages of the signals received via the non-inverted and the inverted terminal during reception of this communication signal.

Abstract: A method for displaying the quality of a digital communications link for field devices of automation technology on a field device serving as a monitoring unit. According to the method telegrams are transmitted via the communications link and are tapped in the monitoring unit and tested according to at least two criteria. The result of the testing is displayed as a bar chart on the monitoring unit, so that the user can observe quality of the communications link simply and easily.

Abstract: A tank side monitor includes two processor boards, a main/communication board, containing field communications interface circuitry and interface circuitry, and an optional IS module, containing HART interface circuitry. The two processor boards are link by an optically coupled serial communications bus. The HART circuitry is multiplexed and can be operated by either the Main/Communication board processor or a local processor on the HART IS board. The optional IS module, an extension of the HART IS board, provides options such as an IS 4-20 mA input or output or other IS I/O. The TSM employs a modular approach for hardware and software, whose implementation consists of a number of modules and programs, the first being the Main/Communications board software. Other programs are contained within the HART interface module. Due to the modular approach taken in the hardware design, the software is also modular and operates on two hardware modules: Main/Communications module software; and HART module software.