Patent GB-1307189-A (GB)
Title: Programme control system for controlling jumping operations of a programme control equipped with stepping mechanism
IPC: G05B19/08
Filed: 1971-04-19
Abstract: 1307189 Programmed electric control systems SPRECHER & SCHUH A G 19 April 1971 [2 April 1970] 22131/71 Heading G3N In a programmed control system employing a stepping mechanism 1 Fig. 1 such as a shift register having input lines a, b &c. and output lines a', b' etc. which can be selectively connected by diodes to input and output rails E and A respectively arranged transversely of the lines to form input and output matrices, there is provided a control circuit 5 which operates a control device 4 to advance the stepping mechanism independently of input line stepping signals, and jump one or more switching stages of the stepping mechanism, at the same time blocking output to the rails A from those stages which are jumped. Switching or advance from one stage to the next successive stage normally occurs in response to information received at the input matrix or cross over network from an installation to be controlled or by programmed information. During the occurrence of a "jump" signal the control device 4 causes shift register 1 to continuously switch from one stage to next without considering whether the switching conditions for the stages have been fulfilled or whether the output lines for those stages have received any command signals. A plurality of transmitters responsive to a process condition and connected to input rails E may decide when a "jump" should take place. Signals from these transmitters in respective rails E are delivered in a logical switching operation to an information input line 13 which then carries a binary "O" or "L" signal indicating whether or not a jump operation is to be performed. This. "decision" signal is fed to a storage circuit 6 (flip-flop FF1) which in turn delivers an appropriate signal to an AND gate 8 the output P of which upon coincidence of a jump decision signal and a jump instruction signal from a line 14, controls the device 4. In operation, assuming that device 4 will effect advance by one step when a "O" signal input is received and that the register 1 advances normally when the control device 4 receives an "L" signal. If say, steps two to five are to be jumped when the input rail E1 carries a logic "L" signal, then diodes D 1  D 12  D 15  are plugged into positions as shown. When shift register 1 switches to the second step then a pulse shaper 10 (monostable FF) receives a logic "L" signal from a "jump instruction" line 14 and delivers a pulse to input C 1  of a flip-flop FF2. The output of FF2 is thus an "L" signal to AND gate 8 the first input of which still carries a "O" signal from FF1, being the initial state of FF1 at the commencement of a process course. The output FF2 is also fed to C 1  of FF1 via a pulse shaper 9 of an interrogation circuit and the information signal in line 13 is read-in thereby to FF1. When rail E 1  carries an "L" signal then line 13 carries a "O" so that input K receives a "O" and input I due to inverter 11 receives an "L" signal. Thus on receiving the read-in pulse from 9 the output of FF1 and hence the first input of gate 8 is an "L" signal. AND gate 8 therefore produces a "O" jump command signal to control device 4 and jumping is effected. Upon reaching the fifth stage, the shaper 10 again receives from line 14 a logic "L" and delivers a pulse to FF2 which is thereby reset, giving a "O" output. As a result the gate 8 has an "L" output which allows the shift register to switch normally from one stage to the next. A clearing signal may be applied at Q after a jumping operation, leaving the circuit 5 ready for any further jumping operation. If during a cyclic process the jumping is to be repeated then signal Q is not applied. A control circuit with selectable interrogation time period and a blocking circuit for blocking jump instructions and the control device 4, are described with reference to Fig. 4 (not shown). A plurality of circuits 5 for triggering jump operations, may be provided, in which case a blocking circuit is employed to permit only one jump command at a time. Each output rail A may be coupled via a power amplifier with a positioning element, e.g. a relay or protective device of an installation to be controlled.