JP3257623B2 - Remote IO system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a remote IO system in which an input / output unit and a control execution unit are separately arranged. More specifically, the present invention relates to a remote IO system that has been improved to improve communication efficiency between an input / output unit and a control execution unit.

[0002]

2. Description of the Related Art In various control systems including a distributed control system, an input / output unit via an input / output signal of a plant is distributed and arranged in the plant. It is separated from the input / output unit. The control execution unit communicates with the input / output unit to control the plant. A system in which the control execution unit and the input / output unit are separately arranged is referred to as a remote IO system. Remote IO
In the system, communication is required between the control execution unit and the input / output unit to obtain data from the plant. In the conventional remote IO system, this communication was executed asynchronously with the control cycle of the control execution unit. Further, the communication cycle was constant regardless of the type of input / output, for example, whether the input was used for plant control or the input was for plant monitoring only. For this reason, the conventional remote IO system has the following problems. Since the data collection cycle is asynchronous with the control cycle, the time until the input from the plant is used by the control execution unit is the data collection cycle in the worst case. Further, the time until the input from the plant is used by the control execution unit is not constant. Since communication is performed at a fixed cycle regardless of the type of input / output, unnecessarily high-speed communication is possible even for inputs that may be performed at regular data collection cycles, such as monitoring-only inputs. Data may be updated periodically.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and divides data to be collected into data to be collected at high speed and data other than the data, and starts a control cycle. High when a certain time ago
Data collection before starting the control cycle.
Complete the collection, and complete the high-speed data collection.
Remote IO system that minimizes and constants the time until the input from the plant is used by the control execution unit by returning to the data collection, and improves the communication efficiency between the control execution unit and the input / output unit. The purpose is to realize.

[0004]

SUMMARY OF THE INVENTION The present invention is a remote IO system having the following configuration. An input / output unit that is distributed in the plant and passes through the input / output signals of the plant, and is separated from the input / output unit to communicate with the input / output unit and control the plant A data execution unit that collects data input from the input / output unit, information defining an input / output unit that performs regular data collection, and control of the control execution unit. Before the cycle starts,
A data storing unit that stores information defining an input / output unit that performs high-speed data collection, and a control cycle of the control execution unit. A communication driver that instructs the data collection means to perform high-speed data collection and completes data collection before the control cycle starts,
The data collection unit receives high-speed data collection instructions from the communication driver, performs high-speed data collection based on information defining the input / output unit that performs the high-speed data collection, and completes high-speed data collection. A remote IO system wherein the definition of an input / output unit to be used is returned to the definition of an input / output unit for performing regular data collection.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing one embodiment of the present invention.
In FIG. 1, PLT is a plant to be controlled, and a sensor S
N1, SN2, valves V1, V2, etc. are installed.
Reference numeral 1 denotes an input / output unit which is distributed and arranged in the plant and passes input / output signals of the plant. The input / output unit 1 converts a signal obtained from a sensor in the plant into digital data, provides the digital data to a higher-level device, and returns communication from the higher-level device to the plant. 2 communicates directly with the input / output unit 1;
It is a data collecting means for collecting data input from the server. A communication driver 3 issues a command to the data collection unit 2 to control communication performed by the data collection unit 2 and extracts data from a communication result executed by the data collection unit 2. Reference numeral 4 denotes a control execution unit that executes a control operation using data and the like obtained from the communication driver 3 and controls the plant based on an operation amount and the like obtained by the operation. Reference numeral 5 denotes a communication time calculation unit that calculates the time required for communication between the input / output unit 1 and the control execution unit 4 based on the type and number of the input / output units 1. 6 and 7
Is a definition storage unit that stores information defining what input / output unit is connected to the data collection unit 2.
The definition storage unit 6 stores information defining an input / output unit that performs regular data collection such as when collecting plant monitoring data. The definition storage unit 7 stores information defining an input / output unit that performs high-speed data collection such as when collecting control data. Control execution unit 4
Performs control of the plant, collects control data from the plant, executes PID control calculation or the like using the collected control data, and controls the plant based on the manipulated variable obtained by the calculation. The definition storage means 6 and 7 can be read and written from the data collection means 2. Reference numeral 8 denotes a definition storage unit that stores information defining all the input / output units whose input / output units are connected to the data collection unit 2, and is readable and writable from the communication driver 3.

The operation of the apparatus shown in FIG. 1 will be described. FIG. 2 is a time chart showing the operation procedure. The operation will be described with reference to this time chart. During the initialization process, the communication driver 3 reads information that defines all input / output units from the definition storage unit 8 and uses the read information as input data for performing regular data collection such as when collecting plant monitoring data. The information is divided into information defining an output unit and information defining an input / output unit that performs high-speed data collection such as when collecting control data, and provides the information to a data collection unit 2. In the process (1), the communication driver 3 uses the communication time calculation means 5 to calculate the time required to collect data from the input / output unit defined to be collected at high speed. The calculation time is defined as tcom. The data collection unit 2 stores the transmitted definition of the input / output unit in the definition storage units 6 and 7 as instructed by the communication driver 3. The communication driver 3
The data collection unit 2 is instructed to start data collection, and the data collection unit 2 performs regular data collection based on the contents of the definition storage unit 6 according to the instruction. The communication driver 3 monitors the control cycle of the control execution unit 4 and instructs the data collection means 2 to perform high-speed data collection before a predetermined time twait at which the control cycle starts. How to calculate the time twait will be described later. The data collection unit 2 changes the definition of the input / output unit used for communication from the regular use (the definition stored in the definition storage unit 6) to the high-speed use (the definition stored in the definition storage unit 7) according to the instruction in Start high-speed data collection. When the high-speed data collection is completed, the definition of the input / output unit used for communication is returned to the normal use, and the normal data collection is resumed. The communication driver 3 reads input / output data from the data collection means 2 at the start of the control cycle. At this time, the latest data has already been collected according to the instruction.

Here, a method of calculating the time t _wait will be described. The time t _wait is originally equal to the time t _com ,
If the communication with the input / output unit 1 fails for some reason, a retry is performed, so that it is necessary to allow some time margin. The margin of the time is defined as _terror . T _{wai t} is given by the following equation in consideration of a margin of time. t _wait = t _com + t _error

[0008]

According to the present invention, the following effects can be obtained.
When a certain period of time before the control cycle starts, high-speed data
Data collection and data collection before the start of the control cycle.
Is completed, the time from when data is input to the input / output unit to when the control execution unit uses the data can be minimized. Further, this time can be made substantially constant. By dividing the collected data into data to be collected at high speed and other data, necessary data can be collected quickly when needed. Conversely, data that does not need to be collected at a high speed can be collected using a free time during which high-speed data collection is not performed. Thereby, the communication efficiency between the control execution unit and the input / output unit can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of the present invention.

FIG. 2 is a time chart for explaining the operation of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 I / O part 2 Data collection means 3 Communication driver 4 Control execution part PLT plant

Claims (1)

(57) [Claims] An input / output unit distributed in a plant and passing input / output signals of the plant, and separated from the input / output unit to perform communication between the input / output unit and in remote IO system and a control execution unit that executes the control of the plant, a data collecting means for collecting the data input from said input unit, and the information defining the input and output unit for performing constant data collection, the
Data collection is completed before the control execution unit control cycle starts
The definition storage means for storing the information defining the input and output unit which performs to keep high-speed data acquisition, monitoring the control cycle of the control execution unit, said data collection upon reaching predetermined time before the control cycle is started A communication driver that instructs the means to perform high-speed data collection and completes data collection before a control cycle starts, wherein the data collection means receives a high-speed data collection instruction from the communication driver. And, high-speed data collection is performed based on information defining the input / output unit that performs the high-speed data collection, and when the high-speed data collection is completed, the definition of the input / output unit used for communication is changed to the input / output unit that performs the regular data collection. A remote IO system characterized by reverting to a definition.