Protection circuit for a data transmission system

Abstract

A bi-directional data transmission system in which the magnitude of the data signals transmitted from a data device is monitored and data transmission to and from the data device is interrupted when the magnitude of the signal exceeds a pre-selected level is disclosed. The system includes a protective network coupling a data device and a data transmission circuit. The protective network includes a conductor providing a path for data signals which enter and leave the data device via the transmission circuit. A control circuit is positioned in the data path for receiving the data signals entering and leaving the data device via the transmission circuit and for providing a binary control signal which is dependent solely on the magnitude of the data signal leaving the data device. The system further includes a switch controlled by the binary control signal for completing the data carrying path provided by the conductor when the magnitude of the data signal leaving the data device is less than a pre-selected level and for interrupting the data carrying path when the data signal leaving the data device is greater than a pre-selected level. The system also includes a load simulator which is incorporated into the network by the switch when the switch interrupts the data path thereby enabling the control circuit to continually sample the data signal leaving the data device and provide the control signal.

Dependencies are inferred from the claim text.