Process control system with analog output control circuit

A digital computer based process control system including an analog output control circuit and digital computer means for supplying digital data and control signals to said output control circuit, said analog output control circuit comprising:

• a plurality of digital data input terminal means for receiving digital data signals from said computer means;
• a plurality of gating means corresponding in number to said input terminal meas, said gating means each having one input connected to a corresponding one of said input terminal means;
• a plurality of digital data-to-pulse duration converters, each of said converters having a plurality of digital data input means corresponding in number to said plurality of gating means;
• means connecting the output of each of said gating means to a corresponding one of the input means of all of said converters;
• signal responsive logic control means including means responsive to address signals derived from signals supplied by said computer means, and to strobe and direction signals also supplied by said computer means;
• said signal responsive logic control means being connected to control the enabling of said gating means;
• said signal responsive logic control means being further connected to control the selective operation of said converters in accordance with the control signals supplied from said computer means;
• and
• pulse duration-to-current converter means connected to the output of each of said digital data-to-pulse duration converters, thereby to provide an output current which is a function of said digital data input signals.