Data processing: generic control systems or specific application – Generic control system – apparatus or process – Plural processors
Reexamination Certificate
1998-12-22
2001-12-04
Grant, William (Department: 2121)
Data processing: generic control systems or specific application
Generic control system, apparatus or process
Plural processors
C700S007000, C700S011000, C700S020000, C700S025000, C709S216000
Reexamination Certificate
active
06327509
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a programmable controller that is now widely in use for the control in steel, paper manufacturing plants, such public systems as water supply and drainage, industrial systems such as automobile industry.
2. Description of the Related Art
The conventional data communication for exchanging data among programmable controllers (hereinafter, referred to as PC) is described with reference to FIG.
8
. When making the data communication between programmable controllers PC
1
and PC
2
, an address was designated so far corresponding to the construction of equipment such as register numbers (REG. NO.) or device numbers stored in a data storage means of the subject programmable controllers PC
1
and PC
2
. That is, the data exchange using actual functional names (logical names of variables) such as limit switch, emergency shutdown switch, etc. that were used in programs was so far not performed.
A defect of a conventional method described above is that it is not able to access specific data unless being always aware of the internal structure/program structure of an object PC. Even when a PC to be subject to the data communication is a PC that executes a similar program, if a program construction and a memory arrangement differ even slightly, it is necessary to change an access method.
Further, if a communicating PC's program is changed when it is under the execution, there is no means to follow the change.
On the other hand, when data are exchanged in a name of variable, if the arrangement of a subject variable in the other controller is changed, a method to correct it automatically will become necessary. When another program is programmed using a name of variable, it is convenient to gain access to a variable by designating that variable name from the viewpoint of the programming but it is troublesome to obtain an actual address of a variable from a demanded variable name and a time is also needed and furthermore, an address of a variable may possibly be changed constantly with the PC program change in the other controller and it becomes necessary to cope with it and therefore, this method is actually not in practical use.
SUMMARY OF THE INVENTION
The present invention has been made in view of the circumstances described above and it is an object to provide a programmable controller that is able to gain access to data by a variable name and also using official variable names on the communication means.
In order to achieve the object described above, a programmable controller of the present invention is capable of transmitting data between own controller and other controllers, each of which comprises a data storage means to store data required for controlling, a program memory for storing a sequential program, a communication interface for communication with a mating controller and a central processing unit for executing the sequential program and controlling the execution thereof, wherein the program controller is characterized in that it is provided with a variable name conversion means to convert a variable name that is an actual functional name into a physical address when a variable access is demanded to the own controller from the other controller.
According to the above mentioned invention, it becomes possible to access data by a variable name that is actual functional name as the variable name conversion means is provided. Thus, it becomes very convenient from the viewpoint of the programming.
The variable name conversion means comprises an access variable name storage means for storing variable names to execute a variable access in the data of a data storage means in the other controller; an access demanded variable name storage means for storing variable names of the data when the variable access is demanded to the data in a data storage means of the own controller from the other controller; an accessed variable name storage means for storing variable names of the data in the data storage means that are approved by the own controller for the other controller to access the data from the outside; a variable name agreement detecting means to detect the agreement between a variable name stored in the access demanded variable name storage means and a variable name stored in the accessed variable name storage means when the variable access is demanded to the own controller from the other controller, and output an agreement detect signal when the agreement is detected; and a physical address conversion means to convert the agreement detected variable name in the accessed variable name storage means into a physical address in the data storage means when an agreement detecting signal is output from the variable name agreement detecting means.
According to the above mentioned invention, when the own controller is demanded by the other controller to gain access to data by a variable name, that variable name is converted into a physical address stored in the data storage means and it becomes possible to gain access to the data by a variable name between the own controller and the other controller.
Further, a programmable controller according to the invention, wherein it is characterized in that by adding a conversion approving/prohibiting means, and when a physical address corresponding to a variable name of an accessed data in the own controller is changed, the address conversion in the physical address conversion means is suspended temporarily by a command of the central control means and then, the contents of the physical address corresponding to variable name code in the physical address conversion means is rewritten and thereafter, make the physical address conversion from the variable name to the approved state.
According to the above mentioned invention, if a physical address corresponding a variable is changed by any program change, the access of a variable name is enabled by to rewrite the physical address irrespective of the change in the program of the controller in the side to access the variables.
Further, a programmable controller according to the invention, a programmable controller is characterized in that by adding information on data type and number of data to a variable name of the accessed data, after a variable name is converted to a physical address output corresponding to data type and number of data in the physical address conversion means and the access corresponding to various data type and number of data is enabled.
According to the above mentioned invention, it becomes possible to gain access corresponding to data type and number of data as index designation is included in a variable name.
Another variable name conversion means comprises an access variable name storage means for storing variable names to execute a variable access in the data of a data storage means in the other controller; an access demanded variable name storage means for storing the variable names when the variable access is demanded to the data storage means of the own controller from the other controller; an accessed variable name storage means for storing variable names of the data in the data storage means that are approved by the own controller for the other controller to access from the outside; a variable name agreement detecting means for detecting the agreement between a variable name stored in the access demanded variable name storage means and a variable name stored in the accessed variable name storage means when the variable access is demanded to the own controller from the other controller, and output an agreement signal when the agreement is detected; a physical address conversion means for converting the agreement detected variable name in the accessed variable name storage means into a physical address in the data storage means when the agreement detecting signal is output from the variable name agreement means; a variable name storage means for storing a plurality of variable names, data type and number of data; and a data access control means for transferring variable names to the access d
Grant William
Kabushiki Kaisha Toshiba
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Rodriguez Paul
LandOfFree
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