Abstract: The apparatus detects error in transceivers of individual modules connected to a communication network, the network being a two-line network. The apparatus comprises a reference voltage source to output a first and second reference voltage value in response to a control signal. A controller controls a predefined sequence of steps in performing a test to detect the errors of the transceivers. A first and second comparator compares a voltage of the corresponding first and second line to a select first and second reference voltage as commanded by the sequence of steps of the test sequence.

Abstract: A system has at least one output device, the output device having a first set of output terminals connected to a corresponding field device. Each output device has a corresponding redundant output device having a corresponding first set of output terminals connected to the same corresponding field device as the corresponding output device. The output device and the redundant output device each have a second set of output terminals corresponding to the first set of output terminals, the second set of output terminals being connected to an apparatus for controlling the information outputted from the first set of output terminals. The apparatus comprises a plurality of switching elements, having a set of first and second contact points. Each of the second set of output terminals of the output device being connected to a corresponding first contact point, and the second set of output terminals of the redundant output device being connected to the corresponding second contact point.

Abstract: A primary slave IOP, upon detecting an error, verifies the availability of a secondary slave IOP, and then sets an output control signal to indicate backup is requested. The primary slave IOP then takes itself out of being the primary. A secondary slave IOP, sensing that the output control signal from the other IOP has been set, assumes the roll of the primary slave IOP. A master controller, detecting an error with the primary slave IOP, interrogates the primary and secondary slave IOPs for a status input, and then arbitrates between the first and second IOP to determine the IOP that is to take on the primary role. Finally the master controller awards the more operational IOP the role of the primary slave IOP, thereby completing the failover operation.

Abstract: An A/D converter circuit generates a precise digital signal which accurately corresponds to an analog input signal. The A/D converter comprises a converter element, having a first and second, input terminal for receiving control signals, and having an output terminal, and further having at least one analog input terminal. The analog input signal is coupled to the analog input terminal, for converting the analog input signal to an uncorrected digital signal. The uncorrected digital signal includes inaccuracies of the parameter differentials of the converter element. A memory unit, stores information defining the actual parameter values of the converter element. A processor, controls the conversion of the analog input signal to the precise digital signal, wherein the actual parameter values are applied to the uncorrected digital signal thereby removing the inaccuracies of the converter element to obtain the precise digital signal.

Abstract: In a process control network, apparatus and method for periodic testing of a thermocouple element includes a switching mechanism that inserts a circuit with known parameters in series with the thermocouple. Voltages levels with and without the inserted circuit are compared and used to identify a failed or failing thermocouple.