US 5,297,134 A · Loop mode transmission system with bus mode backup

Abstract

A transmission system formed by a master station and a plurality of satellite stations which are connected by a transmission line into a loop, the data and command signals from the master station being passed sequentially from station to station around the loop. A failure in a satellite station that prevents further loop transmission is detected by watchdog timers in one or more successive stations. As a result, the stations detecting the failure switch themselves into a bus-mode of operation, the master station switches itself and the remaining stations into the bus-mode of operation. The switching back to the loop-mode of operation can be performed under control of the master station automatically, upon detection that the failure has been corrected. The switching also can be performed under external command.

Claims16

Dependent claims

A transmission system for transmitting data and control signals comprising:

a master station operative for transmitting control signals and for transmitting and receiving data signals;
a plurality of satellite stations operative for receiving and transmitting control and data signals;
transmission means connecting said master station and said satellite stations sequentially in a loop, each of said satellite stations being connected for receiving said control and data signals and for transmitting said signals to the following station in said loop;
means for detecting an abnormality in at least one station;
and
means responsive to said detection to switch said system from a loop transmission mode to a bus transmission mode, which enables each of the satellite stations to directly communicate with the master station.

3 more elements

Dependencies are inferred from the claim text.

Loop mode transmission system with bus mode backup

Life of this patent

Loop mode transmission system with bus mode backup

Life of this patent

Abstract

Claims16