JP3160975B2 - Distributed control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a decentralized control device for controlling a process amount such as temperature and pressure, and more particularly, to a control operation unit for performing various control operations and a control operation unit separated therefrom. A data bus connecting between the control operation unit and the remote input / output device in a device including a plurality of remote input / output devices which are arranged in a distributed manner and exchange signals with sensors and actuators; It relates to transmission control of a remote input / output bus.

[0002]

2. Description of the Related Art A distributed control device is configured to input a large number of signals from a process to be controlled and to output operation signals to a large number of control terminals, and to comprehensively monitor the entire controlled object. A plurality of remote input / output devices are coupled to the control operation unit according to the nature of the task to be performed so that the user can perform and control.

[0003] Here, a shared memory is provided between the control operation unit and the remote input / output device, which allows read / write access from both of them. In order to maintain (equalize) the contents of the data buffer used by the microprocessor and the input / output data on the remote input / output device side equally, cyclic scan transmission is performed for each remote input / output device. ing.

[0004] Such a cyclic scan transmission is
(A) which input / output point of the input / output device corresponds to which address in the shared memory; (b) which input / output point has what cyclic scan transmission cycle;
(C) What kind of transmission service (input data reading, exchange of output data and readback data, etc.) is to be executed at which input / output point, and the transmission is performed in accordance with a preset transmission condition.

[0005] In this type of conventional device, when the power supplied to the device is interrupted and then restored, the microprocessor in the control operation unit again performs the cyclic scan transmission as described above. Was configured to do.

[0006]

In the conventional device having such a configuration, when the power is restored from a power failure, the microprocessor in the control operation unit performs various operations for power restoration. It takes a considerable amount of time before normal transmission control using the remote input / output bus is performed.
There was a problem that recovery to normal process control operation was delayed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a distributed control device capable of quickly recovering to a normal process control operation when a power supply is restored from a power failure. The purpose is to:

[0008]

According to the present invention for achieving the above object, the present invention provides a control operation unit (1) which is in charge of a control operation, and is connected to the control operation unit via a remote input / output bus (RB). Remote input / output devices (PO1, PO2, PO3
...), the input / output data handled by the control operation unit 1 and the input / output data on the remote input / output device side using the remote input / output bus in a normal control operation state. Normal transmission support with cyclic scan transmission to ensure that
A-bis means (41), and first performs transmission for outputting emergency, continued transmission service means for performing normal cyclic scan transmission service Once that is complete (42), first
An initialization start transmission service means (43) for performing a cyclic scan transmission for input to an input, an interruption time measuring means (44) for measuring a transmission interruption time of the remote input / output bus, and an interruption time measuring means. If the measurement result is shorter than a predetermined time, the transmission service switching unit activates the continuous transmission service unit, and if the measurement result by the interruption time measurement unit is longer than the predetermined time, the transmission service switching unit activates the initialization start transmission service unit ( 45), a distributed control system which is characterized that you a provided.

[0009]

When the power supply of the apparatus is interrupted, transmission on the remote input / output bus is interrupted. The interruption time measuring means is
The transmission status on the remote input / output bus is monitored for each remote input / output device, and the time during which transmission is interrupted is measured. Here, when the transmission interruption time is shorter than the predetermined time and the transmission is instantaneous interruption, the continuous transmission service means is driven. If the transmission interruption time is longer than a predetermined time, the initialization start transmission service means is driven to perform transmission control for reading a signal from a sensor or a current actuator output value (readback value).

In this way, at the time of transmission interruption recovery, transmission service switching control is performed depending on the transmission interruption time,
Smooth recovery to normal control operation is realized.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a configuration block diagram showing one embodiment of the present invention. In the figure, CNT is a control operation device in charge of control operation, PO1, PO2, PO3... Are a plurality of remote input / output devices connected to the control operation device CNT via a remote input / output bus BS. Are arranged in a distributed manner with respect to the control arithmetic unit CNT, and are configured so that an input signal is applied from various sensors installed in the field and an operation signal is output to an actuator such as a valve.

In the control operation unit CNT, reference numeral 1 denotes a control operation unit (processor) which is in charge of, for example, PID control operation and sequence control operation, and 2 denotes a power supply circuit in the control operation unit CNT which supplies power to each unit. . Reference numeral 3 denotes a non-volatile shared memory, which allows read / write access from the control operation unit 1 and a plurality of remote input / output devices PO transmitted via a remote input / output bus BS.
The input / output data from 1, PO2, PO3,... Is cyclically written at a period of oversampling with respect to the operation period of the control operation processor 1.

Reference numeral 4 denotes a transmission control unit for controlling transmission of the remote input / output bus BS. In this transmission control unit, 41
Is a remote input / output bus BS in a normal control operation state.
, Normal transmission service means for performing cyclic scan transmission for maintaining the input / output data handled by the control operation unit 1 and the input / output data on the remote input / output device side equally, 42 Is a continuous transmission service means for first performing only the urgent output transmission and then performing a normal cyclic scan transmission service when the transmission is completed. 43 is an initialization start transmission service for performing only the first cyclic scan transmission for input. Means. Each of these means is realized by a transmission control microprocessor.

Reference numeral 44 denotes interruption time measuring means for measuring the transmission interruption time of the remote input / output bus BS. The interruption time measuring means is constituted by a battery-backed-up timer so that the operation continues even when the power from the power supply circuit 2 is interrupted. Have been. A transmission service switching control unit 45 activates the continuous transmission service unit 42 when the measurement result by the interruption time measurement unit 44 is shorter than a predetermined time, and causes the interruption time measurement unit 44 to operate.
If the measurement result in is longer than the predetermined time, switching control is performed to activate the initialization start transmission service means 43. Reference numeral 46 denotes a communication interface, which is configured so that input / output data is converted into a normal bit-serial signal to the remote input / output bus BS, transmitted in a predetermined format, and receives these signals.

The operation of the apparatus having the above configuration will be described below. (Operation in Normal Control Operation State) The normal transmission service means 41 in the transmission control unit 4 maintains the input / output data handled by the control operation unit 1 and the input / output data on the remote input / output device side equal. Is performed to perform the cyclic scan transmission. This cyclic scan transmission is performed cyclically at a cycle of oversampling with respect to the control calculation cycle of the control calculation processor 1, and a plurality of remote input / output devices PO1, PO
2, the input / output data from PO3, etc. are written, and the contents are updated.

The control processor 1 reads out input / output data written in the shared memory 3 in a control calculation cycle, performs a predetermined control calculation using these data, and stores the calculation result in the shared memory. Write to 3. The output data written to the shared memory 2 by the control operation unit 1 is transmitted to a plurality of remote input / output devices PO1, PO2, PO3.
... sent to the remote input / output devices PO1, PO2, P
This is reflected in the operation of the actuator connected to O3.

By such an operation, for example, a control operation in which the degree of opening and closing of a valve (valve) is controlled following the calculation result of the control calculation unit 1 is performed. It should be noted that which of the plurality of remote input / output devices PO1, PO2, PO3,... Corresponds to which address position in the shared memory 3 and what kind of transmission service is to be provided is determined in advance when the operation of the device is started. It is assumed that the setting is made for each remote I / O device. (Operation When Momentary Transmission Disruption Occurs) The interruption time measuring means 44 monitors the transmission status on the remote input / output bus BS for each remote input / output device, and the transmission interruption time is determined by a predetermined time. If it is shorter than the time, it is determined that the transmission is momentarily interrupted. In this case, the transmission service switching control unit 45 drives the continuous transmission service unit 42. The continuous transmission service means 42 first performs transmission for output urgently, and after the transmission is completed, shifts to normal cyclic scan transmission. Here, for which output point the emergency output transmission is performed, and if a transmission error occurs in the emergency output transmission, the transmission will be performed again, but conditions such as up to the specified number of times are determined in advance. It shall be set. (Operation when transmission interruption occurs for a long time) The interruption time measuring unit 44 monitors the transmission status on the remote input / output bus, and determines that the transmission interruption time is longer than a predetermined time. In this case, the transmission service switching control means 45
Starts the initialization start transmission service means 43.
The initialization transmission service means 43 first performs only cyclic scan transmission for input (including readback for actuator output) and updates input data. After the transmission limited to such input is completed,
The control calculation unit 1 updates output data as a calculation result,
Shift to normal transmission service.

In this way, the transmission service switching control section 45 individually controls the switching of the operation by the transmission service means depending on the transmission interruption time for each remote input / output device. FIG. 2 is an explanatory diagram of a basic operation mode of the normal transmission service unit 41, the continuous transmission service unit 42, and the initialization transmission service unit 43. Each of the transmission service means performs the above-described transmission service depending on the transmission interruption time, and has the following basic operation modes.

Transmission stop mode: This mode is entered when no power is transmitted to the remote I / O device and the control operation unit loses power at all. Recovery confirmation transmission mode: A state in which transmission (input / output transmission) for an application is not performed, and it is attempted to confirm whether frame transmission between the control operation unit 1 and each remote input / output device is possible.

When the power of the control operation unit 1 is restored, the mode shifts from the transmission stop mode to this mode. Transmission service mode: a state in which transmission (input / output transmission) for an application is being performed (normal transmission service state). When a recovery response is received from the remote input / output device or when a power recovery notification is received from the remote input / output device, the mode shifts from the recovery confirmation transmission mode to this mode.

In this transmission service mode, when no response from the remote input / output device continues for a specified number of times or more,
Alternatively, when the power failure notice signal is output from the remote input / output device, the mode shifts from this mode to the recovery confirmation transmission mode.

Here, the interruption time measuring means (timer) 4
4 is to start timing when the mode is shifted from the transmission service mode to the recovery confirmation transmission mode, and to stop timing when the recovery processing in the recovery confirmation transmission mode is completed, and to set the time between them as the transmission interruption time. Operation shall be performed.

[0023]

As described in detail above, the present invention provides
When the power is restored from a power failure, the most appropriate transmission service means is configured to be activated depending on the transmission interruption time, and according to the present invention, it is possible to rapidly recover from the transmission interruption state. In addition, it is possible to provide a distributed control device capable of promptly shifting to a normal process control operation.

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram of a basic operation mode of a normal transmission service unit, a continuous transmission service unit, and an initialization transmission service unit.

[Explanation of symbols]

 CNT Control operation device PO1, PO2, PO3 ... Plurality of remote input / output devices BS Remote input / output bus 1 Control operation unit (processor) 2 Power supply circuit 3 Non-volatile shared memory 4 Transmission control unit 41 Normal transmission service means 42 Continuous transmission service Means 43 Initialization start transmission service means 44 Interruption time measurement means 45 Transmission service switching control unit 46 Communication interface

Claims (1)

(57) [Claims] A control operation unit (1) in charge of control operation
And remote input / output devices (PO1, PO2, P2) connected to the control operation unit via a remote input / output bus (RB).
O3 ...), the input / output data handled by the control operation unit 1 and the input / output of the remote input / output device using the remote input / output bus in a normal control operation state. A normal transmission service means (41) for performing cyclic scan transmission so as to keep data equal, and a transmission for urgently outputting first, and when the transmission is completed, a normal cyclic scan transmission service is provided. A continuous transmission service means (42) for performing a transmission , an initialization start transmission service means (43) for first performing a cyclic scan transmission for input, and a disruption time measuring means for measuring a transmission disruption time of the remote input / output bus ( 44), when the measurement result by the interruption time measuring means is shorter than a predetermined time, the continuous transmission service means is activated, and the interruption time If the measurement result of the measuring means is longer than the predetermined time, the transmission service to start the initialization start transmission service means
Scan switching unit (45), a child and includes distributed control system according to claim.