Data processing: generic control systems or specific application – Generic control system – apparatus or process – Plural processors
Reexamination Certificate
1998-12-11
2001-04-10
Grant, William (Department: 2121)
Data processing: generic control systems or specific application
Generic control system, apparatus or process
Plural processors
C700S002000, C700S009000, C700S095000
Reexamination Certificate
active
06216046
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to a method for controlling successive machine processes, wherein at least first and second decentralized process control units for different machine processes are connected to one another and to a central control unit.
2. Description of the Prior Art
Such successive machine processes play a part, for example, in the automatic equipping of substrates (such as printed circuit boards or ceramic substrates) with components such as SMD (surface mounted device) components or BGA (ball-grid arrays). The individual components are taken from a magazine or a delivery device with an equipping head and are then positioned in a predetermined position on the substrate.
In this process execution, a large number (approximately 20-30 per component) of successive machine processes are implemented, many of these only being allowed to be implemented if the machine process sequencing earlier in time was successfully completed. Such process sequences also occur in further automatic processing units required in the equipping process such as, for example, for applying glue points onto substrates. For monitoring this compulsory sequence of the machine processes, the individual control units that control and monitor the individual decentralized machine processes are connected to a central control unit that monitors the entire process execution. Each individual control unit communicates the end of the machine process which it controls to it to the central control unit, and the central control unit subsequently communicates a start command to the control unit responsible for the following machine process. Since, however, the central control unit controls a number of machine processes sequencing in parallel, and sequences additional tasks such as, for example, communication with an operator of the automatic equipping unit, time delays between the reception of the end signal from a first decentralized control unit and the output of the start command to a second decentralized control unit occur. Given a large number of successive machine processes, considerable losses of time, and thus equipping performances that are too low, arise. In addition, the communication between the decentralized control units and the central control unit occupies takes time that reduces the equipping performance.
One possibility for shortening the time would be to provide different central control units for different tasks, for example one central control unit controls tasks an additional central control unit for communication between the operator and the machine and for data editing. Communication among the various central control units, as would be necessary in such an approach, however, would still require an undesirable time expenditure.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method for the above type of process control
The above object is achieved in accordance with the principles of the present invention in a method for controlling successive decentralized machine processes, each decentralized machine process having a decentralized control unit responsible for controlling that process, wherein a central control unit transmits a start command for a first of the decentralized machine processes to a first decentralized control unit, the first decentralized control unit starts the first decentralized machine process and transmits a start signal to the central control unit, during the execution of the first decentralized machine process, the central control unit transmits a preparatory command to a second decentralized control unit which is responsible for controlling a second of the decentralized machine processes. The preparatory command includes at least one start condition for the second decentralized machine process which is satisfied upon reception of a completion signal by the second decentralized control unit from the first decentralized control unit, indicating completion of the first decentralized process. The second decentralized control unit then starts the second decentralized machine process after reception of the aforementioned completion signal.
In the inventive method, one or more decentralized control units for successive machine processes are informed of the completion of the preceding machine process as by the decentralized control unit which is responsive for that preceding machine process, the reception of this completion signal being a part of the start condition. Without a detour via the central control unit, the decentralized control units exchange the satisfaction of these start conditions with one another. The central control unit distributes its commands—given the assumption of undisturbed execution—early enough so that they are present in the respective decentralized control unit before the start conditions are met. The delay is then defined only by the transmission between the individual decentralized control units and is correspondingly short.
As a result of the concentration of various jobs (control and operation) in a central control unit (and thus in a computer), which is enabled without loss of time as a result of the invention, costs for the hardware as well as for the software are saved. Only one central control unit, is employed, for which only one standard operating system is used.
A number of start conditions can be communicated to a simple decentralized control unit. As a result, a machine process which requires a number of machine processes be successfully executed before it can begin executing can be taken into consideration in the overall control procedure.
A flow chart for the machine processes can be stored in the central control unit, with the central control unit logging the proper execution on the basis of answerbacks by the decentralized control units. As a result, the central control unit is able to initiate an error routine given the occurrence and recognition of errors in the process execution.
The inventive method can be especially simply implemented in an embodiment wherein the central control unit and the decentralized control units are connected to one another by a bus capable of multi-address calling. A bus capable of multi-address calling has the property that each periphery device (control unit) connected thereto monitors the communication which is ensuing on the bus, but evaluates only the signals and commands which are relevant to that control unit. The signals and commands thus need not be transmitted multiply, but only once.
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patent: 5867388 (1999-02-01), Okumura et al.
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Haas Gerhard
Huber Wolfgang
Pruefer Martin
Bahta Kipest
Grant William
Schiff & Hardin & Waite
Siemens Aktiengesellschaft
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