A new signal transmitting method for Fieldbus

The purpose of this work is to provide a method to increase the number of connectable devices for the Fieldbus. We have proposed a new signal transmitting method, which has features to reduce driven current during non-transmission and raise average driven current to a level which generates the required signal voltage during transmission. In this method, since the average current changes according to whether the transmission occurs or not, vibrations are generated on the bus. The frequency of the bus vibration can be filtered out. But this filter influences on the low-frequency part of the receiving signal, and also degrades the jitter of the digitalized signal. In this paper, we simulated the influence on the receiving signal by the jitter and obtained the filter characteristics that reduces the influence of the jitter to a minimum, and showed that there is no problem to the new signal transmitting method