CA2818367A1 - Input/output unit and control system - Google Patents
Input/output unit and control systemInfo
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- CA2818367A1 CA2818367A1 CA2818367A CA2818367A CA2818367A1 CA 2818367 A1 CA2818367 A1 CA 2818367A1 CA 2818367 A CA2818367 A CA 2818367A CA 2818367 A CA2818367 A CA 2818367A CA 2818367 A1 CA2818367 A1 CA 2818367A1
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
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- Safety Devices In Control Systems (AREA)
Abstract
An input/output unit includes: an input/output device that transmits, in response to a control request frame, a control response frame to a control device; a first conversion device that is included in a first system communication path and converts the control request frame to an electrical signal; a second conversion device that is included in the first system communication path and converts the control response frame to an optical signal; a third conversion device that is included in a second system communication path and converts the control response frame to an optical signal; and a fourth conversion device that is included in the second system communication path and converts the control request frame to an electrical signal. The third conversion device obtains a reception status at the first conversion device and transmits the reception status to the control device.
Description
=
NAGAI & ASSOCIATES
111250426 (A120052/CAO) INPUT/OUTPUT UNIT AND CONTROL SYSTEM
INCORPORATION BY REFERENCE
100011 The disclosure of the following priority application is herein incorporated by reference: Japanese patent application no 2012-133558 filed June 13, 2012.
BACKGROUND OF THE INVENTION
NAGAI & ASSOCIATES
111250426 (A120052/CAO) INPUT/OUTPUT UNIT AND CONTROL SYSTEM
INCORPORATION BY REFERENCE
100011 The disclosure of the following priority application is herein incorporated by reference: Japanese patent application no 2012-133558 filed June 13, 2012.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention [0003] The present invention relates to an input/output unit and a control system.
[0004] 2. Description of Related Art [0005] A control system used in a workplace where the first priority is given to safety assurance, such as a chemical plant or a nuclear power plant, needs to clear rigorous requirements imposed on its availability (characteristics defined to indicate how well the particular system is able to withstand trouble, also referred to as an availability factor), since if the system goes down due to any type of trouble, a serious accident may result.
Japanese laid open patent publication no. 2011-113415 discloses a technology whereby better availability is assured by connecting a plurality of RIO (remote input/output) units in a duplex circuit system achieved through a duplex CPU device configuration.
SUMMARY OF THE INVENTION
Japanese laid open patent publication no. 2011-113415 discloses a technology whereby better availability is assured by connecting a plurality of RIO (remote input/output) units in a duplex circuit system achieved through a duplex CPU device configuration.
SUMMARY OF THE INVENTION
[0006] FIG 5 is a block diagram showing the structure disclosed in Japanese laid open patent publication no. 2011-113415, i.e., a block diagram of the structure that includes a plurality of RIO (remote input/output) units (input/output units) in a duplex circuit system achieved through a duplex CPU device configuration. If an optical cable Si and an optical cable S4 become cut off from each other, the locations where the abnormality (error) has occurred must be detected through a two-step procedure by first detecting the error in the optical cable S4 and then detecting the error in the optical cable Si only after the problem in the optical cable S4 has been corrected in the structure disclosed in Japanese Laid Open Patent Publication No. 2011-113415.
[0007] According to the first aspect of the present invention, an input/output unit comprises: an input/output device that controls a control target device in response to a control request frame originating from a control device, and transmits, in response to the control request frame, a control response frame to the control device by superimposing the NAGAI & ASSOCIATES
111250426 (A120052/CAO) control response frame upon an electrical signal; a first conversion device that is included in a first system communication path and converts an optical signal, upon which the control request frame transmitted via the first system communication path is superimposed, to an electrical signal; a second conversion device that is included in the first system communication path and converts the electrical signal, upon which the control response frame is superimposed, to an optical signal; a third conversion device that is included in a second system communication path and converts the electrical signal, upon which the control response frame is superimposed, to an optical signal; and a fourth conversion device that is included in the second system communication path and converts an optical signal, upon which the control request frame transmitted via the second system communication path is superimposed, to an electrical signal. The first conversion device transmits, in response to a status request frame originating from the control device, a status response frame including a reception status of the optical signal to the control device by superimposing the status response frame upon an electrical signal;
the second conversion device converts the electrical signal with the status response frame superimposed thereupon, which is transmitted by the first conversion device, to an optical signal; the fourth conversion device transmits, in response to a status request frame originating from the control device, a status response frame including a reception status of the optical signal to the control device by superimposing the status response frame upon an electrical signal; and the third conversion device converts the electrical signal with the status response frame superimposed thereupon, which is transmitted by the fourth conversion device, to an optical signal, obtains, from the first conversion device, the reception status at the first conversion device and transmits, in response to a status request frame originating from the control device, a status response frame including the reception status at the first conversion device to the control device by superimposing the status response frame upon an optical signal.
100081 According to the second aspect of the present invention, a control system comprises: an input/output unit according to claim 1; and the control device.
The control device decides that the first system communication path has a fault if the control device does not receive the status response frame returned by the first conversion device within a predetermined length of time following transmission of the status request frame to the first conversion device.
BRIEF DESCRIPTION OF THE DRAWINGS
NAGAI & ASSOCIATES
111250426 (A120052/CA0) [0009] FIG 1 is a block diagram showing the structure of the control system according to the present invention.
[0010] FIG 2 shows the structure of a communication frame.
[0011] FIG 3 presents a communication time chart pertaining to communication carried [0012] FIG. 4 presents a communication time chart pertaining to communication carried out in an error state.
[0013] FIG. 5 is a block diagram of the structure adopted in a control system in the prior art.
DESCRIPTION OF PREFERRED EMBODIMENT
[0014] FIG 1 shows the structure of a control system that includes RIO units (input/output units) according to the present invention. The control system, which includes a CPU unit 5A, a CPU unit 5B, an RIO unit 1, an RIO unit 2 and an RIO
unit 3 is [0015] The CPU unit 5A includes a CPU device (control device) Al and electro-optical conversion devices A31 and A32. The CPU device Al is connected to the electro-optical conversion device A31 via a system-1 electrical cable A21 and is also connected to the electro-optical conversion device A32 via a system-2 electrical cable A22. As will be =
NAGAI & ASSOCIATES
111250426 (Al 20052/CA0) optical cable side and also transmit a frame having been received through the optical cable, toward the electrical cable side. Namely, the electro-optical conversion devices A31 and A32 each achieve switchovers between electrical signals and optical signals, upon which the request frames R and the response frames A are superimposed. While the electrical-side interface is configured so as to enable integrated transmission/reception, transmission and reception are carried out independently of each other through the optical-side interface. Each electro-optical conversion device can be independently disengaged. This means that even when the electro-optical conversion device connected to the system-1, for instance, malfunctions and needs to be replaced, the system can operate without interruption with the electro-optical conversion device A32 connected to the system-2. The two electro-optical conversion devices A31 and A32 are connected with each other via a link bus A33, which is an electrical cable enabling information exchange between the two electro-optical conversion devices A31 and A32.
[0016] The CPU unit 5B assumes a structure similar to that described above.
The command device 4 controls the CPU device Al and a CPU device B1 via the command line 41, by designating either one as a main system and designating the other as a subsystem.
[0017] The RIO unit 1 includes an RIO device 11, and electro-optical conversion devices 121, 122, 141 and 142. The RIO device 11 is connected to the electro-optical conversion devices 121 and 141 through a system-1 electrical cable 131 and is also connected to the electro-optical conversion devices 122 and 142 through a system-2 electrical cable 132.
An operator 150 and a sensor 151 are connected to the RIO device 11 and the operator 150 and the sensor 151 are also connected to a control target device. As are the electro-optical conversion devices included in the CPU units, two of the electro-optical conversion devices included in the RIO unit 1, i.e., the electro-optical conversion devices 121 and 122, are connected with each other via a link bus 123 and the other two electro-optical conversion devices 141 and 142 in the RIO unit 1 are connected with each other via a link bus 143. The RIO unit 2 and the RIO unit 3 adopt structures similar to that of the RIO unit 1.
[0018] FIG 2 shows a communication frame. A start flag Fl indicates a starting point of the frame. A CPU, an RIO or an electro-optical conversion device receives a frame bearing a recipient address F2 matching its own address but does not receive any frame with a recipient address that does not match its own address. It is to be noted that the CPUs, the RIOs and the electro-optical conversion devices are each assigned with a NAGAI & ASSOCIATES
111250426 (A120052/CAO) unique address different from any other address, except for two electro-optical conversion devices, one connected to the system-1, the other connected to the system-2 and connected with each other via a link bus, which bear a single, common address. For instance, the electro-optical conversion device A31 and the electro-optical conversion device A32 are assigned with a common address. The electro-optical conversion device 121 and the electro-optical conversion device 122 also share a single address. A frame transmitted by a CPU, an RIO or an electro-optical conversion device bears its address in a sender address F3. In a type F4, information distinguishing the particular frame as a request frame (REQ) or a response frame (ACK) is provided. A circuit primary station transmits a request frame, and a circuit secondary station responds by transmitting a response frame.
An RIO puts input data or output data in a data F5. In addition, two electro-optical conversion devices connected with each other via a link bus report a system-1 optical reception status and a system-2 optical reception status to each other at all times through data communication carried out via the link bus. This enables each electro-optical conversion device to possess the information on the reception statuses in both system 1 and system 2, which will indicate any error in an optical signal received through either system, at all times. As a result, the electro-optical conversion device is able to place the reception statuses indicating any error in an optical signal received through system 1 or system 2, in the data F5. For instance, the electro-optical conversion device 121 places the information on the system-1 optical reception status corresponding to the optical cable Si, having been collected by the electro-optical conversion device 121 itself, and the information on the system-2 optical reception status corresponding to the optical cable V1, having been collected by the electro-optical conversion device 122 connected to the electro-optical conversion device 121 via the link bus, in the data F5. An end flag F6 indicates an ending point of the frame.
100191 When the CPU device Al is designated as the main system device, the CPU
device Al acts as the circuit primary station that engages in communication with the secondary stations, i.e., the RIO devices 11, 21 and 31, so as to individually prompt the RIO devices 11, 21 and 31 to output data to the corresponding control target devices via operators 150, 250 and 350 respectively and to take in data from the control target devices via sensors 151, 251 and 351 respectively. The CPU device B1 takes in (snoops on) the contents of communication in which the CPU device Al is engaged. The term "snoop", usually meaning "eavesdrop", is used in this context to mean "monitor" a network or the like. The snoop operation is enabled through a function of the electro-optical conversion NAGAI & ASSOCIATES
111250426 (A120052/CAO) devices 121 and 342 that allows them to constantly transmit a frame, addressed to the CPU device Al and received through the optical side, toward both the optical side (the side on which the optical cables Ul and V4 are connected) and the electrical side (the side on which the system-1 electrical cable 131 is connected). The snoop operation is enabled as the frame addressed to the CPU device Al is transmitted to the CPU device B1 via the optical cables Ul and V4. A similar function is provided through the electro-optical conversion devices 122 and 341 when the CPU device B1 is designated as the main system CPU device. Since the electro-optical conversion devices 121, 122, 341 and 342 fulfill a unique function different from that of the other electro-optical conversion devices, they are each notated as E/O-RC in FIG 1. In addition, the electro-optical conversion devices A31, A32, B31 and B32 within the CPU units 5A and 5B, which are also distinct from the other electro-optical conversion devices E/O, are each notated as E/O-CP in FIG
1.
[0020] FIG 3 presents a communication time chart pertaining to a communication frame transmission/reception that may be executed at the CPU unit 5A under normal circumstances. The communication is executed cyclically. The CPU device engages in communication with an RIO device, a system-1 electro-optical conversion device and a system-2 electro-optical conversion device. The CPU device transmits a single request frame R both through the system 1 circuit and the system 2 circuit, whereas the RIO
device transmits a single response frame A both through the system 1 circuit and the system 2 circuit. First, the CPU device transmits a request frame R addressed to an RIO
device via the optical cable Si in the system-1 circuit and via the optical cable T4 in the system-2 circuit. The request frame R, having been transmitted from the CPU
device as described above, is then transferred via the electro-optical conversion devices and sent back to the CPU device. However, since the communication frame bears an address different from its own address, the CPU device does not receive the returning request frame. Next, the CPU device receives a response frame A transmitted from the RIO
device and addressed to the CPU device, via the optical cable S4 in the system-1 circuit and via the optical cable Ti in the system-2 circuit.
[0021] Subsequently, the CPU device transmits a request frame R addressed to a system-1 electro-optical conversion device via the optical cable Si in the system-1 circuit and transmits a request frame R addressed to a system-2 electro-optical conversion device via the optical cable T4 in the system-2 circuit. The request frames R, having been transmitted by the CPU device as described above, are transferred via the electro-optical NAGAI & ASSOCIATES
111250426 (A120052/CA0) conversion devices and sent back to the CPU device. However, the request frames do not bear addresses matching its own address and thus, the CPU device does not receive either of the returning request frames. The electro-optical conversion devices each transmit a frame through the circuit in which the particular electro-optical conversion device is connected. The CPU device receives a response frame A, originating from the system-1 electro-optical conversion device and addressed to the CPU device, via the optical cable S4 in the system-1 circuit and receives a response frame A, originating from the system-2 electro-optical conversion device and addressed to the CPU device, via the optical cable Ti in the system-2 circuit. The time chart in FIG. 3 indicates how such communication is carried over a single cycle. While FIG 3 presents an example of communication carried out by the CPU device with a single RIO, a single system-1 electro-optical conversion device and a single system-2 electro-optical conversion device connected thereto, the CPU device may be in fact connected with multiple RIO devices, system-1 electro-optical conversion devices and system-2 electro-optical conversion devices. In such a case, communication will be carried out repeatedly multiple times, each in correspondence to one of the communication partners connected to the CPU
device. Such communication is indicated with dotted lines in FIG 3. The electro-optical conversion devices (E/Os, E/O-RCs and E/O-CPs) each transmit a response frame through the two circuits, i.e., the optical circuit and the electrical circuit, so as to report the optical reception status to the two CPU devices, the CPU device Al and the CPU device Bl.
[0022] FIG 4 presents a communication time chart pertaining to communication carried out in a state of error. In this "state of error", the optical cables Si and S4 in FIG 1 both have a fault. While normal transmission/reception can be carried out in system 2, full frame reception cannot be achieved in system 1. After transmitting a control request frame or a status request frame, the CPU device Al waits in standby to receive a control response frame from the RIO device or a status response frame from the electro-optical conversion device. If it does not receive the control response frame or the status response frame within a predetermined length of time, it terminates the reception. At this time, a response timeout is detected. The time to elapse between the request frame transmission and the response timeout detection is set as a response timeout length. The response timeout length is set so as to assume a value equal to or greater than the maximum value representing the length of time allowed to elapse after the request frame is transmitted until the response frame is received when the optical cables S1 and S4 are both in a normal state. Based upon the response timeout detected as described above, the =
NAGAI & ASSOCIATES
111250426 (A120052/CAO) CPU device Al decides that the system-1 communication path constituted with the optical cables Sl, S2, S3 and S4, i.e., the system-1 communication path that includes the electro-optical conversion devices 121 and 141, has a fault. Based upon this decision, the CPU device Al is then able to shift into processing for transmitting the next control request frame or status request frame. Likewise, if the system-2 communication path, constituted with the optical cables T 1, T2, T3 and T4, i.e., the system-2 communication path that includes the electro-optical conversion devices 142 and 122, has a fault, the CPU
device Al is able to decide that the system-2 communication path has a fault based upon a response timeout detected in a similar manner. Upon making such a decision, the CPU
device Al is able to shift into processing for transmitting the next control request frame or status request frame regardless of which system communication path has the fault.
[0023] As shown in FIG 1, the RIO unit (input/output unit) 1 according to the present invention includes the RIO device 11, the electro-optical conversion device 121, the electro-optical conversion device 141, the electro-optical conversion device 122 and the electro-optical conversion device 142. The RIO device 11 controls the control target device in response to a control request frame R originating from the CPU
device Al and transmits, in response to the control request frame R, a control response frame A to the CPU device Al by superimposing it upon an electrical signal. The electro-optical conversion device 121, which is included in the system-1 communication path, converts an optical signal upon which the control request frame R transmitted via the system-1 communication path, is superimposed, to an electrical signal, and transmits, in response to a status request frame R originating from the CPU device Al, a status response frame A, including the optical signal reception status, to the CPU device Al by superimposing the status response frame A upon an electrical signal. The electro-optical conversion device 141 converts the electrical signal upon which the control response frame A is superimposed, to an optical signal, and also converts the electrical signal upon which the status response frame A is superimposed, transmitted by the electro-optical conversion device 121, to an optical signal. The electro-optical conversion device 122, which is included in the system-2 communication path, converts an optical signal upon which the control request frame R transmitted via the system-2 communication path, is superimposed, to an electrical signal, and also converts an electrical signal upon which a status response frame A is superimposed, transmitted by the electro-optical conversion device 142, to an optical signal. The electro-optical conversion device 122 further obtains, from the electro-optical conversion device 121, the reception status at the NAGAI & ASSOCIATES
111250426 (A120052/CAO) electro-optical conversion device 121, and transmits, in response to the status request frame R originating from the CPU device Al, the status response frame A
including the reception status at the electro-optical conversion device 121, to the CPU
device Al by superimposing the status response frame A upon an optical signal. The electro-optical conversion device 142, which is included in the system-2 communication path, converts the optical signal upon which the control request frame R, transmitted through the system-2 communication path, is superimposed, to an electrical signal, and also transmits, in response to the status request frame R originating from the CPU device Al, a status response frame A including the optical signal reception status, to the CPU
device Al by superimposing the status response frame A on an electrical signal. This means that even when the optical cables S1 and S4 are both cut off, the CPU device Al is able to detect, based upon the status response frame A originating from the electro-optical conversion device 122 and addressed to the CPU device Al, that the optical cable 51 has a fault. In other words, the present invention provides an RIO unit (input/output unit) that makes it possible to determine a specific location where a circuit fault has occurred.
[0024] In the embodiment described above, data are transmitted and received via the link buses at all times. However, the present invention is not limited to this example. For instance, upon receiving a request frame originating from the CPU device, an electro-optical conversion device may output a status inquiry command, which includes a request for data indicating the optical reception status in the other system, to the electro-optical conversion device in the other system via the link bus, and receive a status report response, which includes data indicating the optical reception status in the other system, transmitted in response. In this case, the need for constantly reporting the optical reception status in the system-1 and the optical reception status in the system-2 to each other, will be eliminated, making it possible to achieve better efficiency in conserving the performance level of the data communication processing via the link bus.
The electro-optical conversion device will then transmit a response frame, prepared in response to the request frame originating from the CPU device, which carries the optical reception status in the other system obtained as described above, as well as the optical reception status in the subject system, to the CPU device.
[0025] Before a switchover between the main system CPU device (CPU device Al) and the subsystem CPU device (CPU device B1) occurs, fault information indicating any malfunction occurring in any of the optical cables Ul through U4 can be collected via the system-2 circuit through data communication enabled via the link buses connecting the NAGAI & ASSOCIATES
111250426 (A120052/CA0) electro-optical conversion devices connected in the system-1 and the electro-optical conversion devices connected in the system-2. The fault information indicating a malfunction in any of the optical cables Ul through U4, collected by the CPU
device B1 as described above, is then provided to the command device 4. As a result, the operator of the command device 4 is able to cancel the CPU device system switchover, so as to preempt a communication failure that would otherwise occur immediately after the switchover and would ultimately disable control of the control target by the CPU device.
[0026] The status of the subsystem CPU device B1 is synchronized with that of the main system CPU device Al on a regular basis in preparation for a CPU device system switchover. The electro-optical conversion device 121, in turn, transmits, in response to the status request frame R originating from the CPU device Al, a status response frame A
including the optical signal reception status to the CPU device Al by superimposing the status response frame A upon an electrical signal, and also transmits the status response frame A including the reception status to the CPU device B1 via the optical cable Ul by superimposing the status response frame A upon an optical signal. In addition, the electro-optical conversion device 123 obtains, from the electro-optical conversion device 121, the reception status at the electro-optical conversion device 121, transmits, in response to the status response frame R originating from the CPU device Al, a status response frame A, which includes the reception status at the electro-optical conversion device 121, to the CPU device Al by superimposing the status response frame A
upon an optical signal, and also transmits the status response frame A, which includes the reception status at the electro-optical conversion device 121 to the subsystem CPU
device Bl, the status of which is synchronized with the status of the CPU device Al, by superimposing the status response frame A upon an electrical signal. The status response frame A
including the reception status at the electro-optical conversion device 121 superimposed upon the electrical signal is superimposed upon an optical signal at the electro-optical conversion device 342 and is transmitted to the subsystem CPU device B1 via the optical cable V4. Through these measures, the CPU device B1 is able to snoop on the response frame transmitted from the electro-optical conversion device to the CPU device Al, which makes it possible to identify the fault location sooner than would be possible through regular status synchronization.
[0027] The above described embodiment is an example, and various modifications can be made without departing from the scope of the invention.
111250426 (A120052/CAO) control response frame upon an electrical signal; a first conversion device that is included in a first system communication path and converts an optical signal, upon which the control request frame transmitted via the first system communication path is superimposed, to an electrical signal; a second conversion device that is included in the first system communication path and converts the electrical signal, upon which the control response frame is superimposed, to an optical signal; a third conversion device that is included in a second system communication path and converts the electrical signal, upon which the control response frame is superimposed, to an optical signal; and a fourth conversion device that is included in the second system communication path and converts an optical signal, upon which the control request frame transmitted via the second system communication path is superimposed, to an electrical signal. The first conversion device transmits, in response to a status request frame originating from the control device, a status response frame including a reception status of the optical signal to the control device by superimposing the status response frame upon an electrical signal;
the second conversion device converts the electrical signal with the status response frame superimposed thereupon, which is transmitted by the first conversion device, to an optical signal; the fourth conversion device transmits, in response to a status request frame originating from the control device, a status response frame including a reception status of the optical signal to the control device by superimposing the status response frame upon an electrical signal; and the third conversion device converts the electrical signal with the status response frame superimposed thereupon, which is transmitted by the fourth conversion device, to an optical signal, obtains, from the first conversion device, the reception status at the first conversion device and transmits, in response to a status request frame originating from the control device, a status response frame including the reception status at the first conversion device to the control device by superimposing the status response frame upon an optical signal.
100081 According to the second aspect of the present invention, a control system comprises: an input/output unit according to claim 1; and the control device.
The control device decides that the first system communication path has a fault if the control device does not receive the status response frame returned by the first conversion device within a predetermined length of time following transmission of the status request frame to the first conversion device.
BRIEF DESCRIPTION OF THE DRAWINGS
NAGAI & ASSOCIATES
111250426 (A120052/CA0) [0009] FIG 1 is a block diagram showing the structure of the control system according to the present invention.
[0010] FIG 2 shows the structure of a communication frame.
[0011] FIG 3 presents a communication time chart pertaining to communication carried [0012] FIG. 4 presents a communication time chart pertaining to communication carried out in an error state.
[0013] FIG. 5 is a block diagram of the structure adopted in a control system in the prior art.
DESCRIPTION OF PREFERRED EMBODIMENT
[0014] FIG 1 shows the structure of a control system that includes RIO units (input/output units) according to the present invention. The control system, which includes a CPU unit 5A, a CPU unit 5B, an RIO unit 1, an RIO unit 2 and an RIO
unit 3 is [0015] The CPU unit 5A includes a CPU device (control device) Al and electro-optical conversion devices A31 and A32. The CPU device Al is connected to the electro-optical conversion device A31 via a system-1 electrical cable A21 and is also connected to the electro-optical conversion device A32 via a system-2 electrical cable A22. As will be =
NAGAI & ASSOCIATES
111250426 (Al 20052/CA0) optical cable side and also transmit a frame having been received through the optical cable, toward the electrical cable side. Namely, the electro-optical conversion devices A31 and A32 each achieve switchovers between electrical signals and optical signals, upon which the request frames R and the response frames A are superimposed. While the electrical-side interface is configured so as to enable integrated transmission/reception, transmission and reception are carried out independently of each other through the optical-side interface. Each electro-optical conversion device can be independently disengaged. This means that even when the electro-optical conversion device connected to the system-1, for instance, malfunctions and needs to be replaced, the system can operate without interruption with the electro-optical conversion device A32 connected to the system-2. The two electro-optical conversion devices A31 and A32 are connected with each other via a link bus A33, which is an electrical cable enabling information exchange between the two electro-optical conversion devices A31 and A32.
[0016] The CPU unit 5B assumes a structure similar to that described above.
The command device 4 controls the CPU device Al and a CPU device B1 via the command line 41, by designating either one as a main system and designating the other as a subsystem.
[0017] The RIO unit 1 includes an RIO device 11, and electro-optical conversion devices 121, 122, 141 and 142. The RIO device 11 is connected to the electro-optical conversion devices 121 and 141 through a system-1 electrical cable 131 and is also connected to the electro-optical conversion devices 122 and 142 through a system-2 electrical cable 132.
An operator 150 and a sensor 151 are connected to the RIO device 11 and the operator 150 and the sensor 151 are also connected to a control target device. As are the electro-optical conversion devices included in the CPU units, two of the electro-optical conversion devices included in the RIO unit 1, i.e., the electro-optical conversion devices 121 and 122, are connected with each other via a link bus 123 and the other two electro-optical conversion devices 141 and 142 in the RIO unit 1 are connected with each other via a link bus 143. The RIO unit 2 and the RIO unit 3 adopt structures similar to that of the RIO unit 1.
[0018] FIG 2 shows a communication frame. A start flag Fl indicates a starting point of the frame. A CPU, an RIO or an electro-optical conversion device receives a frame bearing a recipient address F2 matching its own address but does not receive any frame with a recipient address that does not match its own address. It is to be noted that the CPUs, the RIOs and the electro-optical conversion devices are each assigned with a NAGAI & ASSOCIATES
111250426 (A120052/CAO) unique address different from any other address, except for two electro-optical conversion devices, one connected to the system-1, the other connected to the system-2 and connected with each other via a link bus, which bear a single, common address. For instance, the electro-optical conversion device A31 and the electro-optical conversion device A32 are assigned with a common address. The electro-optical conversion device 121 and the electro-optical conversion device 122 also share a single address. A frame transmitted by a CPU, an RIO or an electro-optical conversion device bears its address in a sender address F3. In a type F4, information distinguishing the particular frame as a request frame (REQ) or a response frame (ACK) is provided. A circuit primary station transmits a request frame, and a circuit secondary station responds by transmitting a response frame.
An RIO puts input data or output data in a data F5. In addition, two electro-optical conversion devices connected with each other via a link bus report a system-1 optical reception status and a system-2 optical reception status to each other at all times through data communication carried out via the link bus. This enables each electro-optical conversion device to possess the information on the reception statuses in both system 1 and system 2, which will indicate any error in an optical signal received through either system, at all times. As a result, the electro-optical conversion device is able to place the reception statuses indicating any error in an optical signal received through system 1 or system 2, in the data F5. For instance, the electro-optical conversion device 121 places the information on the system-1 optical reception status corresponding to the optical cable Si, having been collected by the electro-optical conversion device 121 itself, and the information on the system-2 optical reception status corresponding to the optical cable V1, having been collected by the electro-optical conversion device 122 connected to the electro-optical conversion device 121 via the link bus, in the data F5. An end flag F6 indicates an ending point of the frame.
100191 When the CPU device Al is designated as the main system device, the CPU
device Al acts as the circuit primary station that engages in communication with the secondary stations, i.e., the RIO devices 11, 21 and 31, so as to individually prompt the RIO devices 11, 21 and 31 to output data to the corresponding control target devices via operators 150, 250 and 350 respectively and to take in data from the control target devices via sensors 151, 251 and 351 respectively. The CPU device B1 takes in (snoops on) the contents of communication in which the CPU device Al is engaged. The term "snoop", usually meaning "eavesdrop", is used in this context to mean "monitor" a network or the like. The snoop operation is enabled through a function of the electro-optical conversion NAGAI & ASSOCIATES
111250426 (A120052/CAO) devices 121 and 342 that allows them to constantly transmit a frame, addressed to the CPU device Al and received through the optical side, toward both the optical side (the side on which the optical cables Ul and V4 are connected) and the electrical side (the side on which the system-1 electrical cable 131 is connected). The snoop operation is enabled as the frame addressed to the CPU device Al is transmitted to the CPU device B1 via the optical cables Ul and V4. A similar function is provided through the electro-optical conversion devices 122 and 341 when the CPU device B1 is designated as the main system CPU device. Since the electro-optical conversion devices 121, 122, 341 and 342 fulfill a unique function different from that of the other electro-optical conversion devices, they are each notated as E/O-RC in FIG 1. In addition, the electro-optical conversion devices A31, A32, B31 and B32 within the CPU units 5A and 5B, which are also distinct from the other electro-optical conversion devices E/O, are each notated as E/O-CP in FIG
1.
[0020] FIG 3 presents a communication time chart pertaining to a communication frame transmission/reception that may be executed at the CPU unit 5A under normal circumstances. The communication is executed cyclically. The CPU device engages in communication with an RIO device, a system-1 electro-optical conversion device and a system-2 electro-optical conversion device. The CPU device transmits a single request frame R both through the system 1 circuit and the system 2 circuit, whereas the RIO
device transmits a single response frame A both through the system 1 circuit and the system 2 circuit. First, the CPU device transmits a request frame R addressed to an RIO
device via the optical cable Si in the system-1 circuit and via the optical cable T4 in the system-2 circuit. The request frame R, having been transmitted from the CPU
device as described above, is then transferred via the electro-optical conversion devices and sent back to the CPU device. However, since the communication frame bears an address different from its own address, the CPU device does not receive the returning request frame. Next, the CPU device receives a response frame A transmitted from the RIO
device and addressed to the CPU device, via the optical cable S4 in the system-1 circuit and via the optical cable Ti in the system-2 circuit.
[0021] Subsequently, the CPU device transmits a request frame R addressed to a system-1 electro-optical conversion device via the optical cable Si in the system-1 circuit and transmits a request frame R addressed to a system-2 electro-optical conversion device via the optical cable T4 in the system-2 circuit. The request frames R, having been transmitted by the CPU device as described above, are transferred via the electro-optical NAGAI & ASSOCIATES
111250426 (A120052/CA0) conversion devices and sent back to the CPU device. However, the request frames do not bear addresses matching its own address and thus, the CPU device does not receive either of the returning request frames. The electro-optical conversion devices each transmit a frame through the circuit in which the particular electro-optical conversion device is connected. The CPU device receives a response frame A, originating from the system-1 electro-optical conversion device and addressed to the CPU device, via the optical cable S4 in the system-1 circuit and receives a response frame A, originating from the system-2 electro-optical conversion device and addressed to the CPU device, via the optical cable Ti in the system-2 circuit. The time chart in FIG. 3 indicates how such communication is carried over a single cycle. While FIG 3 presents an example of communication carried out by the CPU device with a single RIO, a single system-1 electro-optical conversion device and a single system-2 electro-optical conversion device connected thereto, the CPU device may be in fact connected with multiple RIO devices, system-1 electro-optical conversion devices and system-2 electro-optical conversion devices. In such a case, communication will be carried out repeatedly multiple times, each in correspondence to one of the communication partners connected to the CPU
device. Such communication is indicated with dotted lines in FIG 3. The electro-optical conversion devices (E/Os, E/O-RCs and E/O-CPs) each transmit a response frame through the two circuits, i.e., the optical circuit and the electrical circuit, so as to report the optical reception status to the two CPU devices, the CPU device Al and the CPU device Bl.
[0022] FIG 4 presents a communication time chart pertaining to communication carried out in a state of error. In this "state of error", the optical cables Si and S4 in FIG 1 both have a fault. While normal transmission/reception can be carried out in system 2, full frame reception cannot be achieved in system 1. After transmitting a control request frame or a status request frame, the CPU device Al waits in standby to receive a control response frame from the RIO device or a status response frame from the electro-optical conversion device. If it does not receive the control response frame or the status response frame within a predetermined length of time, it terminates the reception. At this time, a response timeout is detected. The time to elapse between the request frame transmission and the response timeout detection is set as a response timeout length. The response timeout length is set so as to assume a value equal to or greater than the maximum value representing the length of time allowed to elapse after the request frame is transmitted until the response frame is received when the optical cables S1 and S4 are both in a normal state. Based upon the response timeout detected as described above, the =
NAGAI & ASSOCIATES
111250426 (A120052/CAO) CPU device Al decides that the system-1 communication path constituted with the optical cables Sl, S2, S3 and S4, i.e., the system-1 communication path that includes the electro-optical conversion devices 121 and 141, has a fault. Based upon this decision, the CPU device Al is then able to shift into processing for transmitting the next control request frame or status request frame. Likewise, if the system-2 communication path, constituted with the optical cables T 1, T2, T3 and T4, i.e., the system-2 communication path that includes the electro-optical conversion devices 142 and 122, has a fault, the CPU
device Al is able to decide that the system-2 communication path has a fault based upon a response timeout detected in a similar manner. Upon making such a decision, the CPU
device Al is able to shift into processing for transmitting the next control request frame or status request frame regardless of which system communication path has the fault.
[0023] As shown in FIG 1, the RIO unit (input/output unit) 1 according to the present invention includes the RIO device 11, the electro-optical conversion device 121, the electro-optical conversion device 141, the electro-optical conversion device 122 and the electro-optical conversion device 142. The RIO device 11 controls the control target device in response to a control request frame R originating from the CPU
device Al and transmits, in response to the control request frame R, a control response frame A to the CPU device Al by superimposing it upon an electrical signal. The electro-optical conversion device 121, which is included in the system-1 communication path, converts an optical signal upon which the control request frame R transmitted via the system-1 communication path, is superimposed, to an electrical signal, and transmits, in response to a status request frame R originating from the CPU device Al, a status response frame A, including the optical signal reception status, to the CPU device Al by superimposing the status response frame A upon an electrical signal. The electro-optical conversion device 141 converts the electrical signal upon which the control response frame A is superimposed, to an optical signal, and also converts the electrical signal upon which the status response frame A is superimposed, transmitted by the electro-optical conversion device 121, to an optical signal. The electro-optical conversion device 122, which is included in the system-2 communication path, converts an optical signal upon which the control request frame R transmitted via the system-2 communication path, is superimposed, to an electrical signal, and also converts an electrical signal upon which a status response frame A is superimposed, transmitted by the electro-optical conversion device 142, to an optical signal. The electro-optical conversion device 122 further obtains, from the electro-optical conversion device 121, the reception status at the NAGAI & ASSOCIATES
111250426 (A120052/CAO) electro-optical conversion device 121, and transmits, in response to the status request frame R originating from the CPU device Al, the status response frame A
including the reception status at the electro-optical conversion device 121, to the CPU
device Al by superimposing the status response frame A upon an optical signal. The electro-optical conversion device 142, which is included in the system-2 communication path, converts the optical signal upon which the control request frame R, transmitted through the system-2 communication path, is superimposed, to an electrical signal, and also transmits, in response to the status request frame R originating from the CPU device Al, a status response frame A including the optical signal reception status, to the CPU
device Al by superimposing the status response frame A on an electrical signal. This means that even when the optical cables S1 and S4 are both cut off, the CPU device Al is able to detect, based upon the status response frame A originating from the electro-optical conversion device 122 and addressed to the CPU device Al, that the optical cable 51 has a fault. In other words, the present invention provides an RIO unit (input/output unit) that makes it possible to determine a specific location where a circuit fault has occurred.
[0024] In the embodiment described above, data are transmitted and received via the link buses at all times. However, the present invention is not limited to this example. For instance, upon receiving a request frame originating from the CPU device, an electro-optical conversion device may output a status inquiry command, which includes a request for data indicating the optical reception status in the other system, to the electro-optical conversion device in the other system via the link bus, and receive a status report response, which includes data indicating the optical reception status in the other system, transmitted in response. In this case, the need for constantly reporting the optical reception status in the system-1 and the optical reception status in the system-2 to each other, will be eliminated, making it possible to achieve better efficiency in conserving the performance level of the data communication processing via the link bus.
The electro-optical conversion device will then transmit a response frame, prepared in response to the request frame originating from the CPU device, which carries the optical reception status in the other system obtained as described above, as well as the optical reception status in the subject system, to the CPU device.
[0025] Before a switchover between the main system CPU device (CPU device Al) and the subsystem CPU device (CPU device B1) occurs, fault information indicating any malfunction occurring in any of the optical cables Ul through U4 can be collected via the system-2 circuit through data communication enabled via the link buses connecting the NAGAI & ASSOCIATES
111250426 (A120052/CA0) electro-optical conversion devices connected in the system-1 and the electro-optical conversion devices connected in the system-2. The fault information indicating a malfunction in any of the optical cables Ul through U4, collected by the CPU
device B1 as described above, is then provided to the command device 4. As a result, the operator of the command device 4 is able to cancel the CPU device system switchover, so as to preempt a communication failure that would otherwise occur immediately after the switchover and would ultimately disable control of the control target by the CPU device.
[0026] The status of the subsystem CPU device B1 is synchronized with that of the main system CPU device Al on a regular basis in preparation for a CPU device system switchover. The electro-optical conversion device 121, in turn, transmits, in response to the status request frame R originating from the CPU device Al, a status response frame A
including the optical signal reception status to the CPU device Al by superimposing the status response frame A upon an electrical signal, and also transmits the status response frame A including the reception status to the CPU device B1 via the optical cable Ul by superimposing the status response frame A upon an optical signal. In addition, the electro-optical conversion device 123 obtains, from the electro-optical conversion device 121, the reception status at the electro-optical conversion device 121, transmits, in response to the status response frame R originating from the CPU device Al, a status response frame A, which includes the reception status at the electro-optical conversion device 121, to the CPU device Al by superimposing the status response frame A
upon an optical signal, and also transmits the status response frame A, which includes the reception status at the electro-optical conversion device 121 to the subsystem CPU
device Bl, the status of which is synchronized with the status of the CPU device Al, by superimposing the status response frame A upon an electrical signal. The status response frame A
including the reception status at the electro-optical conversion device 121 superimposed upon the electrical signal is superimposed upon an optical signal at the electro-optical conversion device 342 and is transmitted to the subsystem CPU device B1 via the optical cable V4. Through these measures, the CPU device B1 is able to snoop on the response frame transmitted from the electro-optical conversion device to the CPU device Al, which makes it possible to identify the fault location sooner than would be possible through regular status synchronization.
[0027] The above described embodiment is an example, and various modifications can be made without departing from the scope of the invention.
Claims (5)
1. An input/output unit, comprising:
an input/output device that controls a control target device in response to a control request frame originating from a control device, and transmits, in response to the control request frame, a control response frame to the control device by superimposing the control response frame upon an electrical signal;
a first conversion device that is included in a first system communication path and converts an optical signal, upon which the control request frame transmitted via the first system communication path is superimposed, to an electrical signal;
a second conversion device that is included in the first system communication path and converts the electrical signal, upon which the control response frame is superimposed, to an optical signal;
a third conversion device that is included in a second system communication path and converts the electrical signal, upon which the control response frame is superimposed, to an optical signal; and a fourth conversion device that is included in the second system communication path and converts an optical signal, upon which the control request frame transmitted via the second system communication path is superimposed, to an electrical signal, wherein:
the first conversion device transmits, in response to a status request frame originating from the control device, a status response frame including a reception status of the optical signal to the control device by superimposing the status response frame upon an electrical signal;
the second conversion device converts the electrical signal with the status response frame superimposed thereupon, which is transmitted by the first conversion device, to an optical signal;
the fourth conversion device transmits, in response to a status request frame originating from the control device, a status response frame including a reception status of the optical signal to the control device by superimposing the status response frame upon an electrical signal; and the third conversion device converts the electrical signal with the status response frame superimposed thereupon, which is transmitted by the fourth conversion device, to an optical signal, obtains, from the first conversion device, the reception status at the first conversion device and transmits, in response to a status request frame originating from the control device, a status response frame including the reception status at the first conversion device to the control device by superimposing the status response frame upon an optical signal.
an input/output device that controls a control target device in response to a control request frame originating from a control device, and transmits, in response to the control request frame, a control response frame to the control device by superimposing the control response frame upon an electrical signal;
a first conversion device that is included in a first system communication path and converts an optical signal, upon which the control request frame transmitted via the first system communication path is superimposed, to an electrical signal;
a second conversion device that is included in the first system communication path and converts the electrical signal, upon which the control response frame is superimposed, to an optical signal;
a third conversion device that is included in a second system communication path and converts the electrical signal, upon which the control response frame is superimposed, to an optical signal; and a fourth conversion device that is included in the second system communication path and converts an optical signal, upon which the control request frame transmitted via the second system communication path is superimposed, to an electrical signal, wherein:
the first conversion device transmits, in response to a status request frame originating from the control device, a status response frame including a reception status of the optical signal to the control device by superimposing the status response frame upon an electrical signal;
the second conversion device converts the electrical signal with the status response frame superimposed thereupon, which is transmitted by the first conversion device, to an optical signal;
the fourth conversion device transmits, in response to a status request frame originating from the control device, a status response frame including a reception status of the optical signal to the control device by superimposing the status response frame upon an electrical signal; and the third conversion device converts the electrical signal with the status response frame superimposed thereupon, which is transmitted by the fourth conversion device, to an optical signal, obtains, from the first conversion device, the reception status at the first conversion device and transmits, in response to a status request frame originating from the control device, a status response frame including the reception status at the first conversion device to the control device by superimposing the status response frame upon an optical signal.
2. An input/output unit according to claim 1, wherein:
upon detecting an error in the optical signal upon which the control request frame is superimposed, the first conversion device provides the third conversion device with a report on the reception status indicating the error in the optical signal; and based upon the report provided by the first conversion device, the third conversion device obtains the reception status at the first conversion device.
upon detecting an error in the optical signal upon which the control request frame is superimposed, the first conversion device provides the third conversion device with a report on the reception status indicating the error in the optical signal; and based upon the report provided by the first conversion device, the third conversion device obtains the reception status at the first conversion device.
3. An input/output unit according to claim 2, wherein:
the third conversion device outputs a status inquiry command, which includes a data request pertaining to the reception status at the first conversion device, to the first conversion device; and the first conversion device includes the reception status indicating the error in the optical signal in a status report response generated in response to the status inquiry command and provides the second conversion device with the status report response.
the third conversion device outputs a status inquiry command, which includes a data request pertaining to the reception status at the first conversion device, to the first conversion device; and the first conversion device includes the reception status indicating the error in the optical signal in a status report response generated in response to the status inquiry command and provides the second conversion device with the status report response.
4. An input/output unit according to claim 2, wherein:
the third conversion device obtains, from the first conversion device, the reception status at the first conversion device, transmits, in response to the status request frame originating from the control device, the status response frame, which includes the reception status at the first conversion device, to the control device by superimposing the status response frame upon the optical signal, and also transmits the status response frame, which includes the reception status at the first conversion device to a subsystem control device, a status of which is synchronized with the status of the control device, by superimposing the status response frame upon an electrical signal.
the third conversion device obtains, from the first conversion device, the reception status at the first conversion device, transmits, in response to the status request frame originating from the control device, the status response frame, which includes the reception status at the first conversion device, to the control device by superimposing the status response frame upon the optical signal, and also transmits the status response frame, which includes the reception status at the first conversion device to a subsystem control device, a status of which is synchronized with the status of the control device, by superimposing the status response frame upon an electrical signal.
5. A control system, comprising:
an input/output unit according to claim 1; and the control device, wherein:
the control device decides that the first system communication path has a fault if the control device does not receive the status response frame returned by the first conversion device within a predetermined length of time following transmission of the status request frame to the first conversion device.
an input/output unit according to claim 1; and the control device, wherein:
the control device decides that the first system communication path has a fault if the control device does not receive the status response frame returned by the first conversion device within a predetermined length of time following transmission of the status request frame to the first conversion device.
Applications Claiming Priority (2)
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| JP2012-133558 | 2012-06-13 | ||
| JP2012133558A JP5847023B2 (en) | 2012-06-13 | 2012-06-13 | Input / output unit and control system |
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| CA2818367A1 true CA2818367A1 (en) | 2013-12-13 |
| CA2818367C CA2818367C (en) | 2015-11-17 |
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| JP (1) | JP5847023B2 (en) |
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| CN113505028A (en) * | 2021-07-14 | 2021-10-15 | 珠海格力电器股份有限公司 | Device switching method and device, electronic device and computer readable storage medium |
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| JP6373630B2 (en) * | 2014-04-28 | 2018-08-15 | 株式会社日立製作所 | Relay control system and communication relay method |
| JP6444711B2 (en) * | 2014-12-02 | 2018-12-26 | 株式会社日立製作所 | Control system |
| JP6698404B2 (en) * | 2016-03-30 | 2020-05-27 | 三菱電機株式会社 | Switchboard control device and switchboard system using the switchboard control device |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JPS5870658A (en) * | 1981-10-22 | 1983-04-27 | Nippon Denso Co Ltd | Multiple signal transmission system for car |
| JPS58186801A (en) * | 1982-04-26 | 1983-10-31 | Toshiba Corp | Monitoring, controlling, and transmitting method of plant |
| CN101446608B (en) * | 2007-11-28 | 2011-12-07 | 上海精益电器厂有限公司 | Calibration device for automatic transfer switch controller |
| US8239158B2 (en) * | 2008-08-04 | 2012-08-07 | National Instruments Corporation | Synchronizing a loop performed by a measurement device with a measurement and control loop performed by a processor of a host computer |
| JP5152765B2 (en) * | 2009-02-25 | 2013-02-27 | 株式会社日立製作所 | Line switching device and plant control system |
| JP2011113415A (en) * | 2009-11-27 | 2011-06-09 | Hitachi Ltd | Control system and cpu unit |
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| CN113505028A (en) * | 2021-07-14 | 2021-10-15 | 珠海格力电器股份有限公司 | Device switching method and device, electronic device and computer readable storage medium |
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| CN103491460B (en) | 2016-06-22 |
| JP5847023B2 (en) | 2016-01-20 |
| CN103491460A (en) | 2014-01-01 |
| JP2013257746A (en) | 2013-12-26 |
| CA2818367C (en) | 2015-11-17 |
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