JPH02236757A - Remote i/o station - Google Patents

Abstract

PURPOSE:To improve the flexibility of an abnormality processing and to secure the acceleration of data transfer with a simple and inexpensive constitution by deciding whether or not the input of data from a control part main body stops exceeding prescribed time before performing the data transmission of a leading word, and making output data at this cycle into a fixed value compulsorily when it stops. CONSTITUTION:A CPU 1 executes a transmission processing to the input/output device of data in a memory 3 for transmission periodically by an output designation program. However, the CPU 1 checks the state of a reception flag corresponding to an arbitrary block before issuing the output instruction of the leading word for the arbitrary block. When the most significant bit information of an I/O address in word designation information is set at a fixing instruction when no data is received and also, a flip-flop 6 is set, the fixing of the output data is commanded by the function of an output data fixing decided circuit 7. Thereby, it is possible to improve the flexibility for the abnormality processing and to secure the acceleration of the data transfer even when the abnormality processing is performed in word unit with a simple and inexpensive constitution.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention relates to a main body of a control unit such as a programmable controller (hereinafter abbreviated as PC) or a computer, and an input/output device (as a controlled object). remote I/O to connect
Regarding O station.

(Prior art) In various control fields, input/output devices to be controlled are installed at a distance from the main body of a control unit such as a PC or computer, or the two are separated for reasons such as backup. There are many cases where it is more convenient to keep them separate.

In such a case, a remote 1/0 station is required which exclusively transfers data from the main body of the control unit to the input/output device.

This remote I/O station is required to satisfy the following three points.

■ It is inexpensive because it only transfers data to the input/output device.

■ High-speed data transmission and reception is possible, and the time required for transfer does not affect the system.

■ Appropriate processing is possible in the event of an abnormality, and it is possible to not only check the transmitted and received data, but also be able to respond flexibly even when the received data is interrupted due to a failure of the transmitting station on the control unit main body side, etc.

In contrast, conventional remote I/O stations, in which data transfer to input/output devices is controlled by software using a CPU (Central Processing Unit), are simple and inexpensive to configure, and can handle complex abnormalities. Processing is also possible and highly flexible, which satisfies the above points 2 and 3. However, if you incorporate error processing in units of 1 word into the transfer program, the transfer cycle will be extended by the software processing for determining processing in the event of an error, resulting in faster speeds. It becomes impossible to ensure the quality of the product. For example, if a delay of 10 to 20 μs occurs in one transfer cycle due to the addition of abnormality processing in units of one word to the transfer program, then when transferring 1 kiloword of data, the delay will be approximately 10 to 20 μs.
This results in a ~20ms delay.

This becomes a big problem in systems that require high-speed response.

In addition, the remote I/O station can also be used as a PC transmission station, or it can be configured entirely with dedicated hardware without using a CPU, but the former is expensive and requires less space inside the PC. The overhead caused by the operating system becomes large and the transfer speed becomes slow. Furthermore, the latter has drawbacks such as a complicated configuration that makes it difficult to make it compact, and lacks flexibility in dealing with abnormalities, all of which are impractical.

(Problems to be Solved by the Invention) As described above, there is no conventional remote I/O station that can satisfy all of the above-mentioned requirements (1) to (2) required of this remote I/O station.

Therefore, the present invention aims to provide a remote I/O station that has a simple and inexpensive configuration, is highly flexible in abnormality processing, and can ensure high-speed data transfer even when abnormality processing is performed in units of one word. It is something to do.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides an electrical connection between a control unit main body and an input/output device as a controlled object, and data transmission between the control unit main body and the input/output device. In a remote I/O station that controls transmission and reception, there is a transmission memory that stores received data from the control unit main body, and a data transmission control means that periodically transmits the data in the transmission memory in units of one word to the input/output device. and,
A determining means for determining whether or not reception of data has been interrupted for a predetermined period of time or more from the control unit main body before the data transmission of the first word by the transmission control means; and output data fixed value conversion means for forcibly setting the value to a fixed value.

(Operation) In the present invention having such a configuration, when data is received from the control unit main body, the received data is stored in the transmission memory. Then, the data stored in this transmission memory is periodically transmitted word by word to the input/output device. However, before transmitting the data of the first word, it is determined whether or not data has been interrupted for a certain period of time from the control unit main body.
If the cycle is interrupted, the output data in that cycle is forcibly set to a fixed value.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the overall configuration of this embodiment. In the figure, 1 is a CPU that controls the operation of each part, and 2 is a ROM that stores fixed data such as program data.
and a RAM for storing temporary data; 3;
Reference numeral 4 denotes a transmission memory for storing received data from the main body of the control unit such as a PC or computer, and 4 is a transmission circuit for transmitting and receiving data to and from a transmission station of the main body of the control unit.

Further, 5 is an output port that outputs a signal to the flip-flop circuit 6, and 7 is an output data fixing judgment that determines whether or not to forcibly fix the output data to "0" to the input/output device. The circuit 8 is an I/O interface that controls the transmission and reception of data to and from the input/output device. This I
The /O interface 8 is composed of an address gate 8a for supplying an address to the human output device, an input data gate 8b for inputting data from the input/output device, and an output data gate 8c for outputting data to the human output device.

The CPUI includes a memory section 2, a transmission memory 3,
．． The transmission circuit 4, output port 5, output data fixation determination circuit 7, and I/O interface 8 are connected via bus lines 9 of an address bus, a data path, and a control bus, respectively.

As shown in FIG. 2, the transmission memory 3 is divided into a plurality of (n) blocks each having a fixed length.
The data received from the main body of the control unit is allocated to each block on a frame-by-frame basis.

On the other hand, in the RAM of the memory unit 2, as shown in FIG.
A reception table 21 is created in which a reception flag is set corresponding to each block of the transmission memory 3. The reception flag of this reception table 21 is set to "1" when the contents of the corresponding block are updated by receiving frame data from the control unit main body within a certain period, and is reset to "01" when the contents are not updated. .

Further, an output designation program shown in FIG. 4 is set in the ROM of the memory section 2. That is, the transmission memory 3
The data output specification for is performed in block units. When specifying one block, the frame data in the block is divided into words, and data is specified sequentially from the first word to the last word, completing the data transmission of one block.

Here, as shown in FIG. 5, the information for specifying one word of frame data is the address A1 of the transmission memory 3 which is the storage destination, and the address of the input/output device which is the output destination. It consists of A2. Then, the high-order bit k of I/O address A2 is used as information B that instructs whether or not to forcibly set all output data to "0" when the corresponding frame data is not received, and the remaining 0 to (k-1)
Use bits as actual I/O addresses.

The CPU then periodically executes the process of transmitting the data in the transmission memory 3 to the input/output device using the output designation program shown in FIG. However, before specifying the output of the first word for an arbitrary block, the CPU checks the state of the reception flag corresponding to the block in the reception table 21.

Then, only when this reception flag is reset to "02", a signal is output from the output port 5 and the flip 7
The loop circuit 6 is set.

Thereafter, the CPUI sequentially specifies the data in the block in word units according to the output specification program, reads out the data in the corresponding transmission memory 3, and outputs the data to the output gate 8.
C to the input/output device. However, if the most significant bit information B of the I/O address in the word specification information is set to specify fixation when data is not received, and the flip-flop 6 is set, output data fixation judgment The action of the circuit 7 issues a command to fix the output data, and in response to this command, output data "0" is transmitted from the output gate 8c to the input/output device. The above operation is shown in a flowchart as shown in FIG.

In this manner, in this embodiment, the cPU 1 controls the transmission and reception of data to and from the input/output device using software. Therefore, the configuration is simple and can be made compact, and complex abnormality processing can be easily handled and is highly flexible.

Moreover, if data is not sent from the control unit for a certain period of time due to an abnormality in the transmission station of the control unit, the corresponding block in the transmission memory 3 will not be updated for a certain period of time, and as a result, , the reception flag on the reception table 21 corresponding to the corresponding block is reset.

When transmitting data of an arbitrary block, the CPU 1 first checks the reception flag corresponding to the block, and sets the flip-flop circuit 6 when it is in the reset state. After that, the data in the block is specified in units of words and sent to the input/output device, but with the flip-flop circuit 6 set, the word specification information is set to fix output data when no data is received. If so, the output data is automatically fixed at "0°".

Therefore, the CPU does not need to judge whether data has not been received for each word, and controls the output port 5 on a block-by-block basis to set/set the flip-flop circuit 6.
Just by resetting it, it becomes possible to handle abnormal situations where data is not received. Therefore, the transfer cycle is shortened and high speed can be ensured.

Note that in the above embodiment, the output data when no data is received is
Although the case of fixing to 0'' is shown, the output pattern is not limited to this, and other fixed patterns may be used.Also, by increasing the number of specified bits, multiple types of fixed bits can be output. It is also possible to transmit a pattern.It goes without saying that various modifications can be made without departing from the gist of the present invention.

[Effects of the Invention] As detailed above, according to the present invention, the structure is simple and inexpensive, the abnormality processing is highly flexible, and even when abnormality processing is performed in units of one word, data transfer can be performed at high speed. It is possible to provide a remote I/O station that can ensure security.

[BRIEF DESCRIPTION OF THE DRAWINGS] The figures are diagrams showing one embodiment of this emitting system, in which FIG. 1 is a block diagram showing the overall configuration, FIG. 2 is a configuration diagram of the transmission memory, and FIG. 3 is a block diagram showing the overall configuration. A diagram showing a table formed in a memory section,
FIG. 4 is a flowchart showing the output designation program set in the memory section, FIG. 5 is a diagram showing the format of 1-word designation information, and FIG. 6 is a flowchart for explaining the operation of this embodiment. DESCRIPTION OF SYMBOLS 1... CPU, 2... Memory part, 3... Memory for transmission, 4... Transmission circuit, 5... Output board, 6...
- Flip-flop circuit, 7... Output data fixation judgment circuit, 8... I/O interface, 21... Reception table. Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Claims] Control unit main body and input/output device (I/O) as controlled object
in a remote I/O station that is electrically coupled to a remote I/O station that controls data transmission and reception between the control unit main body and the input/output device, a transmission memory that stores received data from the control unit main body; data transmission control means for periodically transmitting data in the memory to the input/output device word by word; The present invention is characterized by comprising a determining means for determining whether or not the data has been interrupted, and an output data fixing means for forcibly setting the output data to a fixed value when the determining means determines that no data has been received for a certain period of time or more. Remote I/O station.