Data transmission network for process system - uses bidirectional bus coupler between each field device and data bus leading to operating device

摘要

The transmission network using frequency-shift keying modulation is provided between field devices and an operating device. Each field device is coupled to a data bus via a bidirectional bus coupler (60) using identical components in the identical sequence for both directions. Pref. the bus coupler has an opening contact (611,612), an amplifier (621,622), a threshold circuit (631,632) and a retriggerable mono flop circuit (641,642) connected in series for each transmission direction. The output of each amplifier is coupled via a closure contact (651,652) to the terminal (602,601) for the opposite transmission direction. ADVANTAGE - Allows data transmission from remote spaced field devices.