Patent ID: 7786919

Claim:
A system comprising: a voltage-to-frequency converter adapted to: receive an analog input signal that represents a sensor-detected physical property; convert said analog input signal to a converted signal having a constant voltage and a frequency value that varies according to a voltage value of said analog input signal; and transmit said converted signal across an isolation device; and a frequency-to-voltage converter adapted to: receive said converted signal; convert said converted signal to a recovered analog input signal having a voltage value that varies according to said frequency value of said converted signal; transmit said recovered analog input signal to a programmable logic controller; a second voltage-to-frequency converter adapted to: receive an analog output signal adapted to control an actuator from the programmable logic controller; convert said analog output signal to a converted signal having a constant voltage and a frequency value that varies according to a voltage value of said analog output signal; transmit said converted signal across an isolation device; and a second frequency-to-voltage converter adapted to: receive a converted signal; convert said converted signal to a recovered analog output Signal having a voltage value that varies according to said frequency value of said converted output signal; and transmit said analog output signal to said actuator; and an information device communicatively coupled to the programmable logic controller via a network, the information device including a user program adapted to monitor one or more activities of the programmable logic controller, or create, edit, compile or transmit a control program.