JP4789099B2 - Input/Output Devices - Google Patents

Description

The present invention relates to expanding the functionality of an input/output device that is located between a host system and a field device and relays communications between them.

Figures 5 (A) to (C) are functional block diagrams showing an example of a control system using a conventional input/output device. In Figure 5 (A), 1 is a host system, and 2 is a field device to be controlled. 3 is an input/output device, which has a host interface 31 that interfaces communication with the host system 1, and an I/O port 32 that interfaces communication with a lower device.

The input/output device 3 receives write values from the upper system 1 via the upper interface 31 and passes them to the lower device via the I/O port 32, and has a relay function that passes read values from the lower device obtained via the I/O port 32 to the upper system 1 via the upper interface 31.

4A is a logic control device, which forms a subordinate device to the input/output device 3 and communicates with the input/output device 3 via the I/O port 31. This logic control device 4A acquires the write value from the upper system 1 acquired via the input/output device 3 and the field input value from the field device 2, and executes logic calculations for control.

The logic control device 4A passes the calculation results to the field device 2 as field output values, and passes the information required by the higher-level system 1 to the higher-level system 1 as read values via the input/output device 3.

Patent document 1 describes a prior art related to an I/O device that sits between a host system and a field device and relays the communication between them. The technology described in patent document 1 is designed to allow application programs to run without modification, regardless of the configuration of the I/O device to be added.

Japanese Patent Application Publication No. 6-243081

The logic control device 4A is composed of hardware only, or hardware and firmware. The logic program is stored in ROM, not only when it is realized by hardware only, but also when firmware is involved, so the higher-level system 1 cannot arbitrarily change the logic program.

Therefore, if you want to change the contents of the logic control, you need to prepare logic control devices 4B, 4C, etc. that reflect the logic you want to change, as shown in Figures 5(B), 5(C), etc., which makes the system more complicated and increases costs.

Furthermore, when configuring a duplicated system with input/output devices and logic control devices on the working and standby sides, there is a problem that switching errors become large because the system does not support an equalization system that updates the latch value on the standby side in real time based on the latch value on the working side, and the latch values on the working and standby sides are significantly different or shifted significantly when switching.

The problem that this invention aims to solve is to realize an I/O device that has an arbitrary control logic calculation function in one type of I/O device and can easily handle equalization of latch values when duplicated.

In order to achieve this object, the present invention is configured as follows.
1. An input/output device which communicates with a host system via a host interface and with field devices via an I/O port, comprising : an operating side input/output device and a standby side input/output device forming a duplicated system, each of the operating side input/output device and the standby side input/output device having an internal logic control means for directly controlling the field devices, the logic control means having an application means for storing an application program, which is selectively downloaded from the outside and includes program information and input/output setting information, and an execution means referenced by the application means, the input/output device updating information held in an equality information holding means provided in the standby side input/output device via the host system using information held in a latch means provided in the operating side input/output device, and updating information held in a standby side latch means provided in the standby side input/output device using information held in the equality information holding means via a switch means operated by a trigger command from the host system .

As is clear from the above description, the present invention has the following advantages.
(1) Since application programs can be easily downloaded from the host, multiple logic operation functions can be supported with one type of hardware. This allows for flexible support of logic changes made by users.

(2) Various logic calculation functions are realized within the input/output device, eliminating the need for multiple logic control devices that were required in conventional systems to realize different logic calculation functions, and thus reducing the number of parts used. In addition, different logic calculations can be supported simply by changing the application settings, which contributes to cost and environmental friendliness.

(3) Although the logic calculation function is realized by firmware (program), by storing internal instrument information and variable information in advance in the execution means that the program can reference, it is possible to realize performance that is comparable to the calculation processing time of conventional technology (hardware).

(4) It is easy to build an equalization system that updates the latch value on the standby side in real time with the latch value on the working side based on an equalization trigger command from a higher-level system, so there is no need to worry about the conventional problem of the latch values on the working and standby sides being significantly different or misaligned when switching.

The present invention will now be described in detail with reference to the drawings. Figure 1 is a functional block diagram showing one embodiment of an input/output device to which the present invention is applied. Elements that are the same as those in the conventional device described in Figure 5 are given the same reference numerals, and their description will be omitted. The following describes the features of the present invention.

In FIG. 1, 100 is an input/output device whose functions have been expanded by the present invention. The upper interface 101 and the I/O port 102 that communicates with the lower device are the same as those of the conventional device, but the form in which the I/O port 102 directly communicates with the field device 2 is different from that of the conventional device.

103 is a logic control means, and the configuration formed within the input/output device 100 is a feature of the present invention. The logic control means 103 is composed of an application means 104 and an execution means 105 referenced by the program of this application means.

In this way, the input/output device 100 of the present invention is characterized by a configuration that combines a simple input/output function that relays between the upper system 1 and the lower-level field device 2, and a logic control function for the field device 2.

200A, 200B, 200C, ... are application programs stored in appropriate storage means on the upper side, and are the main entities that execute various logic operations processed by the logic control means 103. These programs are selected by a switching means 300 that is operated manually or in response to a command from the upper system 1, and downloaded to the application means 104 of the logic control means 103.

Next, an overview of the overall operation will be given. Written values from the upper system 1 are taken into the input/output function via the upper interface 101 and passed to the logic control means 103. The logic control means 103 performs logic calculations according to the received read values and the application that has been downloaded in advance. The results are passed back to the input/output function, and the input/output function unit outputs the results to the field device 2 as field output values via the I/O port 102.

The field input value is passed to the logic control means 103 via the I/O port 102 and the input/output function. The logic control means 103 executes a logic operation according to the received field input value and the application, and passes the operation result to the input/output function. The input/output function notifies the value as the upper system 1 read value via the upper interface 101.

Furthermore, as with conventional devices, it is also possible to create applications that perform logic calculations by combining values written from the upper system 1 and field input values from the field device 2.

Figure 2 is a functional configuration diagram explaining the cooperation between the application means 104 and the execution means 105. The execution means 105 holds logic elements referenced by the application program 200 downloaded to the application means 104.

The logic elements are basic internal instrument information 105A such as AND devices, OR devices, timer devices, flip-flop devices, etc., and variable information 105B. The application program 200 refers to this execution means 105 to obtain the internal instruments to be used and the variable information required for the calculation. It is also possible to realize a logic calculation function by an application that combines multiple internal instruments.

Here, the downloaded application 200 is stored in EEPROM or RAM, the internal instrument information 105A is stored in ROM, and the variable information 105B is stored in RAM. By preparing the internal instrument information, which is the basic logic, in ROM in advance, the logic calculation speed can be significantly improved compared to writing all calculation information from the upper system to the RAM area and performing calculations while reading it.

Figure 3 is a map diagram showing the data contents of the application program to be downloaded. The data of the application program 200 at the time of downloading consists of input/output setting information 200A and program information 200B.

Since the program information 200B can be treated as part of the input/output setting information 200A, it can be easily set and changed from a higher-level system in the same way as changing conventional input/output setting information. Therefore, there is no need to develop new application download tools, and the conventional engineering environment can be used as is.

Figure 4 is a functional block diagram of a duplex system formed by an active I/O device 100 and a standby I/O device 400. 106 is an active latch means provided on the active I/O device 100 side. 401 is a standby latch means provided on the standby I/O device 400. 402 is an equality information holding means also provided on the standby I/O device.

The upper system 1 periodically acquires the information (latch value) held in the working latch means 106 of the working I/O device, writes it to the equivalent information holding means 402 provided in the standby I/O device, and updates the held information (latch value).

403 is an equalization trigger means, which is provided in the standby side I/O device 400 and receives an equalization command from the upper system 1. 404 is a switch means that is operated by the output of this equalization trigger means.

When the equalization trigger means 403 receives a trigger command from the upper system 1, it turns on the switch means 404, writes the latch value of the equalization information holding means 402 to the standby side latch means 401 provided in the machine side input/output device, and updates the latch value.

To configure such a duplicated system, an equalization application is downloaded in advance to the active and standby I/O devices. The equalization application may be downloaded to both I/O devices, but the equalization application is actually only executed on the standby I/O device.

In this way, by utilizing the functional configuration of the present invention, it is possible to easily realize the equalization process of matching the latch value on the active side with the latch value on the standby side using a host system and an application. The duplication error in this case is only the time between when the host system reads the latch value and when it writes it to the equalization value, which is extremely small compared to the conventional technology and is within the acceptable range.

The function for achieving equalization is not limited to the application download method, but can also be achieved by previously installing other modules with similar functions in the active and standby input/output devices.

1 is a functional block diagram showing an embodiment of an input/output device to which the present invention is applied; FIG. 2 is a functional configuration diagram illustrating cooperation between an application unit and an execution unit. FIG. 4 is a map diagram showing the data contents of an application program to be downloaded. FIG. 11 is a functional block diagram of a duplex system formed by an active input/output device and a standby input/output device. FIG. 1 is a functional block diagram showing an example of a control system using a conventional input/output device.

Explanation of symbols

REFERENCE SIGNS LIST 1 Upper system 2 Field device 100 Input/output device 101 Upper interface 102 I/O port 103 Logic control means 104 Application means 105 Execution means 200A, 200B, 200C... Application program 300 Switching means

Claims (1)

An input/output device that communicates with a host system via a host interface and communicates with a field device via an I/O port,
A duplex system is formed by the active I/O device and the standby I/O device.
each of the active input/output device and the standby input/output device includes a logic control means formed therein for directly controlling the field device;
The logic control means includes application means for storing application programs, which are selectively downloaded from an external device and include program information and input/output setting information, and execution means referenced by the application means;
updating information held in an equivalent information holding means provided in the standby input/output device via the host system with information held in a latch means provided in the working input/output device;
updating information held in a standby side latch means provided in the standby side input/output device with information held in the equivalent information holding means via a switch means operated by a trigger command from the upper system;
1. An input/output device comprising:

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