Process control system with signal conversion to standard intermediate signals carrying data as a function of time duration

In a process control system arranged to accept varied forms of analog sensing signals from a plurality of field sensing devices, to process data represented thereby both digitally and in analog fashion, and to supply varied forms of analog control signals to a plurality of analog field control devices, the improvement which comprises:

• an input signal converter means for each field sensing device for converting data from (a) the varied analog forms generated by the field sensing devices to (b) first input intermediate signals in a standard form arranged to carry data as a function of time duration;
• isolator means for each of said input signal converter means and having an input and an output section;
• means for directing the first input intermediate signal developed by each input signal converter to a respective input section, the associated output section being arranged to provide a second input intermediate signal corresponding directly to the first input intermediate signal fed to said input section but conductively isolated therefrom;
• an input digital interface and storage means for each field sensing device for converting data from (a) the corresponding second input intermediate signal to (b) input digital signals in a form for use by digital data processing means, and for storing the input digital signals for use on demand by the data processing means;
• an output digital interface and storage means for each field control device for storing output digital signals supplied by the data processing means and for converting the output digital signals into first output intermediate signals in a standard form arranged to carry data as a function of time duration;
• analog data processing means;
• means for converting data derived from said second input intermediate signals into input analog signals for use by said analog processing means;
• means for converting output analog signals from said analog data processing means into an additional set of said first output intermediate signals;
• isolator means for each of said output signal converter means and having an input section and an output section;
• means for directing the first output intermediate signals to respective input sections of said isolator means, the output section of each isolator means being arranged to provide a second output intermediate signal corresponding directly to the intermediate signal fed to the input section thereof but conductively isolated therefrom;
• conductively-isolated power supply means supplying power to (1) said input sections of said isolator means for said input signal converter means and (2) said output sections of said isolator means for said output signal converter means;
• an output signal converting means for each field control device for converting said second output intermediate signals into the varied forms of output analog control signals required by the field control devices;
• and
• signal path editing means comprising a plurality of separate input terminal means and a plurality of separate output terminal means;
• means interconnecting selected input terminal means to selected output terminal means to provide a preselected set of signal paths between certain of said input terminal means and certain of said output terminal means;
• said interconnecting means providing for ready alteration of said preselected set of signal paths to any of a number of different sets of signal paths to accommodate variation in required signal transmissions;
• means connecting predetermined output sections of said isolator means to corresponding ones of output terminal means;
• and means connecting each of said output terminal means to said input digital interface and storage means.