Sequence control system and its method

• US 4,972,310 A
• Filed: 02/06/1989
• Issued: 11/20/1990
• Est. Priority Date: 02/05/1988
• Status: Expired due to Fees

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Itoh, Takatoshi, Naitoh, Tatsuo, Kawakami, Takayuki, Kubota, Hisashi, Onodera, Masayuki, Shimizu, Kei
• Primary Examiner(s): Smith, Jerry
• Assistant Examiner(s): GORDON, PAUL P
• Application Number:
  US07/306,580
• Time in Patent Office: 652 Days
• Field of Search: 364/140, 364/141, 364/146, 364/147, 364/436, 364/900, 364/949, 364/926.9, 364/474.02, 364/474.01
• US Class Current: 700/19
• CPC Class Codes: G05B 19/05 Programmable logic controllers, e.g. simulating logic interconnections of signals according to ladder diagrams or function charts

Abstract

To facilitate program control modification and troubleshooting in sequence control system in spite of simple processing programs, sequence control processes are linked in a chain fashion. A unit process for activating an actuation member in both forward and reverse directions forms a ring so as to be activated in sequence cyclically via an execution condition recognizing switches, and these unit process rings are linked between an actuation start side activator for the present process and an actuation end side activator for the preceding process, both activated simultaneously whenever one of them is activated. Therefore, any process can be stopped at, restarted and reversed from any process steps in both the forward and reverse directions through the linked actuation start and end side activators, after the automatic operation has been switched to the manual operation or vice versa. Further, when a plurality of machines are controlled by a single sequencer, it is preferable to selectively connect a single operation board to a necessary robot connector to minimize the robot space and the cost.

Claims

1. A sequence control system for controlling a plurality of processes in sequence, each process being achieved by actuating an actuation member in both forward and reverse directions, which comprises:

(a) forward side executing means for executing a forward process by driving at least one actuation member in the forward direction;

(b) forward side actuating means for determining whether said forward side executing means is ready for execution;

(c) forward side stopping means for stopping said forward side executing means;

(d) reverse side executing means for executing a reverse process by driving the at least one actuation member in the reverse direction;

(e) reverse side actuating means for determining whether said reverse side executing means is ready for execution;

(f) reverse side stopping means for stopping said reverse side executing means;

(g) actuation start side activating means, coupled to said forward side actuating means and said reverse side stopping means and activated when said reverse side stopping means is turned on, for allowing said forward side executing means to be ready for execution when said forward side actuating means is turned on;

(h) actuation end side activating means, coupled to said forward side stopping means and said reverse side actuating means and activated when said forward side stopping means is turned on, for allowing said reverse side executing means to be ready for execution when said reverse side actuating means is turned on, said actuation start side activating means for the present process and said actuation end side activating means for the preceding process being activated simultaneously when one of said actuation start side activating means for the present process and said actuation end side activating means for the preceding process is activated; and

(i) execution condition recognizing means, coupled to said forward side actuating means and said reverse side actuating means, for recognizing a forward side executable condition under which said forward side execution means can be executed when said forward side actuating means determines that said forward side executing means is ready for execution and a reverse side executable condition under which said reverse side execution means can be executed when said reverse side actuating means determines that said reverse side executing means is ready for execution.

2. The sequence control system of claim 1, which comprises;

(a) a sequencer (20) for controlling a plurality of robots provided with respective connecting means, including;

(1) input/output means, connected to a plurality of robots and robot connecting means respectively, for inputting/outputting robot motion information signals to/from the robot;

(2) control means, connected to said input/output means, for controlling an entire operation of the system;

(3) port address setting means, connected to said control means, for setting a port address setting signal;

(4) a plurality of communication enabling means, connected to said control means, said port address setting means, and the robot connecting means, for enabling communication between the connecting means and said control means; and

(b) single operation commanding means selectively connected to one of the connecting means (60) of the plural robots, when said single operation commanding means is connected to one of the connecting means,

wherein said control means recognizes the connecting means of the robot, to which said single operation commanding means is connected, via said input/output means, outputting a port address setting signal from said control means to said operation commanding means via said input/output means to enable communication between said control means and said operation commanding means, and also to enable said port address setting means to determine a communication port (50a) in said communication enabling means (50), so that said single operation commanding means (40) connected to the robot connecting means can input operation command signals to said sequencer via said input/output means and said communication enabling means.

3. A sequence control method, comprising the steps of:

(a) checking whether actuation start side activating means for the present process is activated;

(b) if the actuation start side activating means for the present process is activated, activating actuation end side activating means for the preceding process;

(c) checking again whether the actuation start side activating means for the present process is activated;

(d) if the actuation start side activating means for the present process is not activated, ending a program loop control;

(e) if the actuation start side activating means for the present process is activated, checking whether forward side executing means is ready for execution;

(f) if the forward side executing means is not ready for execution, repeating the above steps (c) to (e);

(g) if the forward side executing means is ready for execution, deactivating actuation end side activating means for the preceding process;

(h) deactivating the actuation start side activating means for the present process;

(i) checking whether an execution condition under which forward side executing means can be executed is recognized;

(j) if an execution condition is recognized, executing forward side executing means;

(k) if an execution condition is not recognized or the forward side executing means is executed,

checking whether the forward side executing means can be stopped;

(l) if the forward side executing means cannot be stopped, repeating the above steps (i) to (k); and

(m) if the forward side executing means can be stopped, activating actuation end side activating means for the present process and actuation start side activating means (P3) for the succeeding process, simultaneously.

4. The sequence control method of claim 3, which further comprises the steps of:

(a) checking whether the actuation end side activating means for the present process is activated;

(b) if the actuation end side activating means is activated, activating the actuation start side activating means for the succeeding process;

(c) checking again whether the actuation end side activating means for the present process is activated;

(d) if the actuation end side activating means is not activated, ending a program loop control;

(e) if the actuation end side activating means is activated, checking whether the reverse side executing means is ready for execution;

(f) if the reverse side executing means is not ready for execution, repeating the above steps (a) to (e);

(g) if the reverse side executing means is ready for execution, deactivating the actuation start side activating means for the succeeding process;

(h) deactivating the actuation end side activating means for the present process;

(i) checking whether an execution condition under which the reverse side executing means can be executed is recognized;

(j) if an execution condition is recognized, executing the reverse side executing means;

(k) if an execution condition is not recognized or the reverse side executing means is executed;

(l) checking whether the reverse side executing mean can be stopped;

(m) if the reverse side executing means cannot be stopped, repeating the above steps (i) to (k); and

(n) if the reverse side executing means can be stopped, activating the actuation start side activating means for the present process and the actuation end side activating means for the preceding process, simultaneously.