JPS6261102A - Executing method for program in programmable controller - Google Patents

Abstract

PURPOSE:To execute the contents of a hardware without changing the contents by accessing the leading address in a fixed memory area, executing a program transferred to a variable memory area if a LOAD instruction exists, and in case of the absence of the LOAD instruction, executing the program located after the leading address of the variable memory area. CONSTITUTION:The variable memory area of a CMOS is set up to locations 4000-7999 and the fixed memory area of a PROM is set up to the location 8000 and after. Locations 0-3999 are assigned to a memory area of a PC system body. Since a ladder of a PC is usually started by the LOAD instruction, a central processing part of the PC accesses the location 8000 at first, and when the LOAD instruction exists, the contents existing in the location 8000 and after the transferred to the location 4000 and after to execute the program in the location 4000 and after. When no LOAD instruction exists, the program in the location 4000 and after is executed as it is.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a program execution method for a programmable controller (hereinafter abbreviated as PC), and more specifically,
This facilitates the execution of sequence programs stored in PROM modules.

[Conventional technology]

PC programs are usually variable, (2K)S-
It is stored in a variable memory of RA~1'8=, but in certain cases it may be required to be stored in a fixed memory such as PROM.

For this reason, in the past, a socket was provided in the PC body and a CMOS memory module was installed.

Two types of memory modules, PROM memory modules, are prepared and replaced with the socket as needed.

[One problem to be solved by the invention] However, in such a conventional example, the P1cogelum located at address 00 (8F), which is not relocatable, is transferred to 900.
(For example, Zilog Corporation 280 falls under this case.)

On the other hand, Intel 8086 works).

As shown in Figure 3, the contents of FROM memory and CMOS
Since the contents of the memory must be stored in the same memory space, address switching and other hardware changes are required.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method that solves these problems and makes it possible to execute a FROM program simply by inserting a PROM into a socket.

[Means for solving problems]

In the present invention, the variable memory area and the fixed memory area are divided and set so that they do not overlap, and the central processing unit of the programmable controller first calls the first address of the fixed memory area, and if there is an "rLOAD" command, then the The contents of r are transferred to a variable memory area, and the program transferred to the variable memory area is then executed.
If there is no ``LOAD instruction'', the program is executed starting from the first address of the 'D] variable memory area.

[For production]

As a result, simply by inserting a FROM module with a fixed sequence into a socket, its contents can be executed without changing the hardware.

〔Example〕

FIG. 1 shows the algorithm of the present invention, and FIG. 2 shows its memory area.

The variable memory area of CMO8 is from address 4000 to 799.
It is set to address 9, and the fixed memory area of FROM is 80.
It is set after address 00.

Addresses 0 to 3999 are the memory area of the PC system body. The processing of the central processing unit described below is executed based on instructions programmed into the memory area of the main body of this PC system.

Now, 1. Normally, the PC ladder starts with the rLOAD command, so the PC's central processing unit first calls address 8000,
rLOAD command, the contents from address 8000 onwards are transferred to address 4000 onwards, and then
Execute the program starting from address 000.

If there is no "rl-XD instruction", the program from address 4000 onward is executed as is.

〔Effect of the invention〕

As described above, according to one aspect of the present invention, there is a great effect that the fixed sequence program of the FROM can be executed simply by inserting the PROM module into a socket or the like without changing the hardware.

[Brief explanation of drawings]

FIG. 1 shows an algorithm of the present invention, FIG. 2 shows a memory map of the present invention, and FIG. 3 shows a conventional memory map showing that address switching is necessary.

Claims (1)

[Claims] In a programmable controller of a type in which a variable memory module and a fixed memory module can be replaced, the variable memory area and the fixed memory area are divided and set so as not to overlap, and the central processing unit of the programmable controller first performs the following steps: Calls the first address of the fixed memory area, and if there is a "LOAD command", transfers the contents from that address to the variable memory area, then executes the program transferred to the variable memory area, and then issues the "LOAD command". 1. A program execution method for a programmable controller, characterized in that if there is no program, a program starting from the first address of a variable memory area is executed.