Method and device for driving multiple latching relays

Abstract

Multiple latching relays are driven on their first side by all but one of the parallel outputs of a shift register. Each relay on the same shift register is driven on its second side by the remaining parallel output of the shift register. A clock signal is fed to all shift registers and causes each shift register to shift all of its information one cell on the selected edge of the clock signal. A latch signal or blanking signal is used to prevent the shift registers from outputting their information to the relays during shifting. A serial data message is inputted to the first shift register and then from the first shift register sequentially to all of the other shift registers. The information in the serial data message is such that after shifting of all shift registers is complete the appropriate signal will be on each side of each latching relay to cause it to either change or remain unchanged. The result is that one serial data line, one clock line and one latching or blanking line controls all of the relays and that additional relays can be controlled simply by adding more shift registers and sending more data down the serial data line.