GB1294326A - Control apparatus for units which become ready for operation at irregular times - Google Patents

Abstract

1294326 Electric selective signalling NATIONAL RESEARCH DEVELOPMENT CORP 29 June 1970 [21 May 1969] 26030/69 Heading G4H A. circuit for providing control signals for a plurality of slow-speed units which become ready for operation at irregular times and then operate in communication with a central high-speed unit on receipt of a control signal comprises a number of stations 10, 11 connected in a loop, at least one unit being associated with each station, each station having a gate circuit to receive an enabling signal from the preceding station and a ready signal indicating that the associated circuit is ready for operation, the circuit providing either an enabling signal for the next station if the associated unit is not ready for operation or a control signal if it is causing the associated unit to operate. When the unit associated with station 10 is ready to operate it provides a signal on terminal 12 enabling And gate 27. The enabling signal is received on the loop input terminal 21 from station 11, and station 10 sends it out again on terminal 22. This signal is inverted at 15 so that a "1" arriving at station 10 on terminal 21 and leaving it as a "1" on terminal 22 is inverted at 15 and circulates round the loop as "0" until it is again inverted at 15. It then circulates as a "1" allowing operation of each station in turn. The enabling signal applied at terminal 21 passes to gate 24 directly and also through delay 25 to produce a delayed output to enable gates 26 and 32. Gate 27 receives the ready signal 12 and the enabling signal on terminal 21, differentiated at 31. The gate output sets a flip-flop 28 to provide another input to gate 32 which produces, on terminal 14 a control signal initiating operation of the slow-speed unit. If the ready signal is not present at 12 the flipflop remains unset and gate 26 then passes the delayed enabling signal to the next station via terminal 22. Gate 26 is connected to the "0" output of flip-flop 28 and remains closed until the flip-flop is reset. When the high-speed unit has finished the work provided by slow-speed unit a signal is given on terminal 13 to reset flip-flop 28. This opens gate 26 passing a signal to terminal 22, which then circulates round the loop as described above.