Fault tolerant interface for safety controls

A method of single wire communication comprising:

• determining a first time interval between a first edge and a second edge of a signal provided by a sensor, wherein the sensor operates in one of a normal state, or an alarm or fault state, wherein the signal corresponds to one of the normal state, or the alarm state or the fault state, wherein a value associated with the signal is predetermined, wherein an edge is one of a transition of the signal from a first voltage to a second voltage or a transition of the signal from the second voltage to the first voltage on a single wire;
• assigning a training pulse value to the first time interval;
• assigning a first bit value to a second time interval, which is a multiple of the first time interval;
• assigning a second bit value to a third time interval associated with a second multiple of the first time interval;
• and
• detecting a plurality of characters, wherein the detection is performed by:
• detecting a pair of edges and determining a current time interval between edges;
• determining whether the current time interval is associated with one of the first time interval, the second time interval or the third time interval;
• and
• assigning the bit value that corresponds to the current time interval based on whether the current time interval is the first time interval, the second time interval or the third time interval.

A fault tolerant interface comprising:

• a system for providing real-time feedback from a plurality of sensors to a safety control;
• wherein:
• the plurality of sensors is configured to provide a signal corresponding to an environmental parameter, wherein the plurality of sensors operates in one of a normal state, an alarm or a fault state, wherein the signal corresponds to one of the normal state, or the alarm state or the fault state, wherein a value associated with the signal is predetermined;
• the safety control is coupled to the plurality of sensors via a single wire, the safety control being configured to transmit serial data to the plurality of sensors and to receive serial data from the plurality of sensors via the single wire in the normal state, wherein the safety control is further configured to detect the alarm state or the fault state based on the signal in addition to decoding the serial data;
• and
• the safety control is configured to determine a data bit associated with a time interval between changes in a voltage level detected on the single wire, the time interval constituting an interval between a rising edge and a falling edge of the voltage level;
• wherein a sensor consistently controls a line until a second sensor takes control of the line from the sensor so that exactly one sensor controls the line at any given time.