JP2000010609A - Programmable controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a programmable controller by which a keep memory is easily initialized at the time of initializing a data memory. SOLUTION: An external nonvolatile memory stores constant number data of the data memory and data of the keep memory in addition to storing a user program and clears input/output data, non-keep memory and system data at the time of initializing the data memory (S1-S3). When the external nonvolatile memory is mounted, copying is executed in the constant number area of the data memory (S4 and S5) and the contents of the external nonvolatile memory are copied at the time of initializing the keep memory when an initialization setting switch is set to copying in the keep memory (S6 and S7). In place of the switch, system setting or setting as data in the constant number data area in the data memory is included.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a programmable controller, and more particularly, to initialization of a data memory used in an operation.

[0002]

2. Description of the Related Art Programmable controllers (hereinafter referred to as P
FIG. 4 shows a case where a user program is executed.
As shown in (1), a program memory PM storing a user program and a data memory DM storing data for calculation are used. Each instruction in the user program indicates an operation on data in the data memory.

[0003] The data memory DM depends on its use.
It is classified into several as follows.

(1) Input / output data This area stores input data fetched from a device external to the PC as digital information, and output data for outputting a calculation result of a user program to the external device.
Generally, all the contents are cleared in the initialization processing of the data memory.

(2) Internal memory This is an area for temporarily storing intermediate calculation results in the process of executing a user program. In the data memory initialization processing, an area for clearing all contents (non-keep memory) and an area for holding contents (keep memory) are provided.

(3) Timer / Counter Current Value When a user program of the PC describes a process using time and number of times, a timer instruction and a counter instruction are used. The timer instruction and the counter instruction require a memory for storing the elapsed time and the number of occurrences of the event. That is this area. In the data memory initialization processing, an area for clearing all contents (non-keep memory) and an area for holding contents (keep memory) are provided. Generally, the current timer value is stored in non-keep memory. The counter current value is used depending on the application. (4) Constants and timer / counter set values This area stores constants used by the user program in calculations and set values of timer / counter instructions. In the data memory initialization processing, it is necessary to hold all the contents.

(5) System Data The OS (Operating System) of the PC notifies the user program of system data (for example, time, error information, control data of each module, etc.), and processes from the user program to the OS. This area is used to store request data. Generally, in the data memory initialization processing, all contents are cleared, and the OS is set again when the user program is started.

As described above, the initialization of the data memory in which the data that needs to be held and the data to be cleared coexist is performed as follows.

The PC initializes the data memory when the power is turned on or when a user program operation is stopped (this is called a STOP mode) and a transition is made to a user program operation state (this is called a RUN mode). In the initialization, the contents may be cleared or held depending on the use of the data memory.

Also, as initialization using an external memory,
There is a method in which a user program is stored in a non-volatile memory such as a ROM, and is transferred to the program memory when power is turned on, and then the processing is started. This is an effective way to avoid destruction of the user program when the user program is sufficiently debugged and fixed.

Similarly, there is a method of storing data in a constant / set value area of a data memory in a non-volatile memory, transferring the data to the data memory when power is turned on, and then starting processing.

According to such a method, the program memory and the data memory do not need to be nonvolatile memories. In other words, it is not necessary to use a battery or the like for holding a power failure, which makes it possible to improve reliability and reduce costs.

[0013]

The conventional method of initializing a data memory has the following problems in handling a keep memory.

In the data memory, the keep memory retains the contents when the power is turned on. However, if a non-volatile external memory is installed and the data memory is stored in the external memory, the contents of the keep memory should be retained as it is when the power is turned on, You have to decide whether to copy.

If the keep memory is used in the same manner as a constant, the contents of the external memory should be copied when the power is turned on, and the operation should always be started using the same value.

When the keep memory is used as an area for storing intermediate data, it may not always be necessary to copy constant data when the power is turned on. In this case, it is desired to retain the data as it was when the power was turned off.

As described above, the initialization method of the keep memory varies depending on how the user program is used. However, this cannot be selectively used in a current PC.

An object of the present invention is to provide a programmable controller that facilitates initialization of a keep memory when initializing a data memory.

[0019]

According to the present invention, in order to solve the above-mentioned problems, an external nonvolatile memory storing data for initializing a data memory is mounted, and a keep memory area of the initialized data is provided. Is set as an initialization setting switch, system setting, or data in a constant data area, and is characterized by the following configuration.

In a programmable controller which initializes the contents of a data memory when power is turned on or when a user program is executed, in addition to storing a user program, an external memory for storing constant data of the data memory and data of a keep memory is provided. Providing a non-volatile memory,
The contents of the external non-volatile memory are copied or left unchanged when the keep memory of the data memory is initialized. Setting means for designating whether or not to do so is provided.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In this embodiment, in addition to storing a user program, an external nonvolatile memory capable of storing initialization data of a data memory is mounted on a PC.
A switch for initialization setting such as a dip switch or short-circuit jumper plug is installed so that it is possible to set whether to copy the contents of the keep memory of the data memory of the external nonvolatile memory to the data memory when the power is turned on. .

The PC provided with the external nonvolatile memory and the initialization setting switch is provided with initialization processing means shown in the flowchart of FIG. 1 for initializing the data memory.

In FIG. 1, when power is turned on (or when a user program shifts to an operation state), input / output data that is not required to be stored among data stored in the data memory is cleared (S1). The non-keep memory is cleared (S2), and the system data is cleared (S3).

Next, the PC checks whether or not an external nonvolatile memory is mounted (S4), and if so, initializes a constant area from the external nonvolatile memory (S4).
5). Subsequently, it is checked whether or not the initialization setting switch is set to the copy side of the keep memory (S6). When the switch is set to the copy side, the keep memory area is initialized from the external nonvolatile memory. (S
7).

Therefore, as for the keep memory, it is possible to set whether or not to copy the contents of the keep memory of the data memory of the external nonvolatile memory to the data memory. The data to be stored can be fixed data like a constant or variable data.

When the keep memory is initialized, copying from an external non-volatile memory eliminates the need to maintain the power failure of the data memory. Therefore, the data memory does not need to maintain a power failure such as a battery, and is excellent in reliability improvement and cost reduction.

FIG. 2 is a flowchart showing another embodiment of the present invention. 1 differs from FIG. 1 in that selection items are prepared in the system settings, and the system settings are replaced with the initialization setting switches in the case of FIG.

In the PC, system settings are set using a programming panel (a so-called loader), and the set data is stored in an internal memory of the PC. This memory is a non-volatile memory and retains its contents even when the power is turned off. The initialization method of the data memory when the power is turned on is stored in this system setting, and when the power is turned on, the contents of the system setting in the nonvolatile memory are checked (S8), and the data memory of the external nonvolatile memory is kept. Enables you to decide whether to copy the contents of memory to data memory.

Also in this embodiment, the data stored in the keep memory can be fixed data like a constant or variable data depending on the use of the user program to be created.

FIG. 3 is a flowchart showing another embodiment of the present invention. This figure differs from FIG. 1 or FIG. 2 in that the necessity of copying is set in a constant area.

The contents of the constant data in the data memory are retained when the power is turned on. When an external memory exists, the contents of constant data in the external memory are always copied to the data memory. That is, the constant data is held in the data memory in any state. Data for setting how to initialize the keep memory is allocated to a specific address of the constant data. Then, when the power is turned on, if the external nonvolatile memory is mounted, after copying the constant data of the data memory from the external nonvolatile memory, the setting of the specific address is checked (S
9), it is determined whether to initialize the keep memory.

[0032]

As described above, according to the present invention, an external non-volatile memory storing data for initializing a data memory is mounted, and whether or not this initialization data is copied to a keep memory area is determined. Are set as initialization setting switches, system settings, or data in the constant data area, so that the data stored in the keep memory can be fixed data such as constants or variable data depending on the use of the user program to be created. For example, the keep memory can be easily initialized when the data memory is initialized.

Further, since the initialization method of the keep memory is copied from the external nonvolatile memory, it is not necessary to maintain the power failure of the battery in the data memory, which is effective in improving the reliability and reducing the cost.

[Brief description of the drawings]

FIG. 1 is an initialization flowchart of a data memory according to an embodiment of the present invention.

FIG. 2 is a data memory initialization flowchart according to another embodiment of the present invention.

FIG. 3 is a flowchart illustrating an initialization of a data memory according to another embodiment of the present invention.

FIG. 4 is a diagram showing a relationship between a program memory and a data memory.

[Explanation of symbols]

 PM: Program memory DM: Data memory

Claims (1)

[Claims] 1. A programmable controller that initializes the contents of a data memory when power is turned on or when a user program is executed. In addition to storing a user program, the programmable controller stores constant data of the data memory and data of a keep memory. An external nonvolatile memory is provided, which is set by an initialization setting switch or is set as data in a system setting or a constant data area in the data memory. When the keep memory of the data memory is initialized, A programmable controller characterized in that a setting means for designating whether to copy the contents or leave the contents as it is is provided.