JP3800322B2 - Distributed control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In the present invention, a connection from a local node connected to a field control station (hereinafter referred to as FCS) in a distributed control device to a remote node in a remote location extended via a communication module is made via a general router or gateway. The present invention relates to a function that enables easy connection.
[0002]
[Prior art]
Based on FIG. 2, a remote node extended connection mode according to the prior art in a distributed control apparatus will be described.
Reference numeral 1 denotes a human interface station (hereinafter referred to as HIS) which is a host device, and 3 denotes an FCS which communicates with the HIS 1 via a control bus 2. Reference numeral 4 is an I / O bus, and 5 is a local node that communicates with the FCS 3 via the I / O bus 4.
[0003]
If necessary, the control bus 2 is extended to another remote control bus 7 via an appropriate communication means 6, and the FCS 8, I / O bus 9, and local node 10 are similarly connected to this control bus. Yes.
[0004]
In the local node 5, the PSU is a power supply module, and the plurality of modules IOM are interface modules that communicate with field devices. The two modules SB401 are communication modules that communicate with the FCS via the I / O bus 4 and are duplicated.
[0005]
The two modules EB401 are communication modules connected to the communication module EB501 of the remote node 12 via the ER bus (10 Mbps Ethernet (registered trademark) (10Base2)) 11 and are duplicated. The ER 11 can be extended to about 2 km at the maximum by the relay means 13 such as an optical repeater.
Similarly, reference numeral 14 denotes a non-redundant ER bus which is connected to another remote node 15. Reference numeral 16 denotes an extension relay means inserted into the ER bus 14.
[0006]
The remote nodes 12 and 15 also have a plurality of input / output interface modules IOM that communicate with the power supply module PSU and field devices, as with the local node 5. The communication module EB 401 of the local node collects (sets) field input / output information via the ER buses 11 and 13 and can refer to it from the FCS 3.
[0007]
[Problems to be solved by the invention]
The extension distance of the ER bus can be extended up to 2 km by relay means such as an optical repeater. However, if the distance to the remote node exceeds 2 km or if the ER bus cannot be laid physically, the remote node Could not be used.
[0008]
An object of the present invention is to realize a distributed control apparatus having a function of freely connecting a remote node without any restriction on the extension distance of a bus by a relay means such as an optical repeater and without a physical laying failure. It is in.
[0009]
[Means for Solving the Problems]
In order to achieve such a problem, a feature of the invention described in claim 1 of the present invention is that in a distributed control device comprising a host device and a field control station that communicates with the host device via a control bus. A local node connected to the field control station via an I / O bus, and one or a plurality of remote nodes connected to the local node via a wide area network, the remote node the self-diagnosis when running the monitoring data update period lies in that the selectable setting above the self-diagnosis period of the local node self-diagnosis period by a user setting of the remote node.
[0010]
The feature of the invention described in claim 2 is that
The wide area network is realized by a leased line service network.
[0011]
The feature of the invention described in claim 3 is that
The wide area network is realized by a wireless LAN.
[0012]
The feature of the invention of claim 4 is that
If there is no response after the no-response monitoring time from the start of communication from the local node to the remote node, it is determined that there is no response and communication is started with the next remote node.
[0013]
The feature of the invention described in claim 5 is that
The remote node is determined to be in an abnormal state when the number of times of no response to the communication from the local node to the remote node exceeds the number of times of no response attempts and there is no continuous response.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a functional block diagram illustrating the configuration of a distributed control apparatus to which the present invention is applied. The same components as those in the conventional apparatus described in FIG.
[0016]
The feature of the present invention is that the local node 5 and the remote node 12 are coupled via the ER bus 11 and the wide area network 17. Reference numerals 17 and 18 denote routers for connecting the duplicated ER bus to the wide area network 17. 20 and 21 are similar routers, and connect the communication module of the remote node and the wide area network 17 via the hubs 22 and 23. In the embodiment, a router is used, but other relay devices such as a gateway may be used.
[0017]
A communication module EB402 with the ER bus 11 in the local node 5 is a communication module dedicated to wide area connection and having a function equivalent to that of the communication module EB401 in FIG.
[0018]
As described above, the ER bus is 10 Mbps Ethernet (registered trademark) (10Base2) (Ethernet (registered trademark) is a registered trademark), and uses the TCP / IP protocol for communication on the line. Therefore, it is possible to easily connect to a general router or gateway commercially available from a network equipment manufacturer.
[0019]
Furthermore, since these routers and gateways are compatible with wide-area networks and wireless communication, it is possible to realize distance extension and non-contact communication by relaying the ER bus with these devices. is there.
[0020]
On the other hand, while the transmission speed of the ER bus is 10 Mbps, the wide area network may not have sufficient transmission capability. In this case, since the transmission delay becomes large, some functions that are affected by the transmission delay cannot be used for the status management and status setting / collection of field devices connected to the IOM of the remote node, or the setting details are changed. It is necessary to take measures such as
[0021]
The wide area network 17 is a dedicated line service network, and assumes a high-speed digital line service (64 k to 6 Mbps), a frame relay service (64 k to 6 Mbps), and the like. This wide area network can be replaced with other relay functions such as a wireless LAN.
[0022]
Next, countermeasures for introducing the wide-area network of the present invention for various functions implemented in the prior art will be described.
(1) IOM start-up procedure Time-up monitoring As for the IOM start-up procedure at the initial startup, each step until the start-up is time-monitored, and if the monitoring time is exceeded, it is determined that the IOM is abnormal.
Regarding the IOM start-up procedure time-up monitoring time when the wide-area network is introduced, the monitoring time of the IOM belonging to the wide-area remote node is extended.
[0023]
(2) Bypass of module status register monitoring at the time of IOM rising Immediately after the IOM is activated, the value of the module status register of the IOM may become indefinite. During this time, the status monitoring of the module status register is bypassed. When the IOM belonging to the wide area compatible remote node rises, the state monitoring time of the module state register is extended.
[0024]
(3) ER bus communication module (EB402) Control right switching condition monitoring The operation state of the connected remote node is collected for each EB402 for the duplexed communication module EB402. The operation status collected by each communication module is compared, and the remote node status collected by the control communication module continues to be worse than the remote node status collected by the standby communication module for more than the control right switching condition monitoring time. If this happens, the control / standby of the communication module is switched. For redundant communication modules, this control right switching condition monitoring time is extended.
[0025]
(4) Duplexed IOM control right acquisition time monitoring For the duplexed IOM, the time until either of the two IOMs becomes the control side is monitored. If there is no IOM to be controlled beyond this time, an IOM abnormality has occurred. For a duplexed IOM implemented in a wide area compatible remote node, the control right acquisition time of the duplexed IOM is extended.
[0026]
(5) Self-diagnosis 1-second rule In the operation monitoring of the IOM, a rule that self-diagnosis is normal if the data update cycle is within 1 second is common. For the IOM installed in the remote node, the self-diagnosis 1 second rule of the data update cycle is extended.
[0027]
Furthermore, a characteristic countermeasure of the present invention when a wide area network is introduced will be described. The following information is prepared as setting information for the communication module EB402.
(1) It is possible to set up to 10 seconds at maximum with the accuracy of no-response monitoring time msec. When the communication module EB402 of the local node 5 starts transmission and the no-response monitoring time is exceeded, it is determined that the communication is no-response, and communication is started to the next remote node.
The no-response monitoring time is set to a value exceeding the response time considered to be a limit in the network system. By making it possible to set this value flexibly, it is possible to connect to all forms of wide-area remote nodes.
[0028]
(2) Number of retries at the time of no response When the remote node continuously responds without exceeding the number of retries, the communication module EB402 determines the state of the node as FAIL (abnormal state).
It is necessary to set the number of no-response retries so that the node does not become FAIL due to a transient abnormality on the communication path (packet loss, data error, unexpected response time, etc.).
From the data error rate of the line relaying the remote node and the probability that the response time exceeds the setting of the no-response monitoring time, it is possible to arbitrarily set the number of retries during no-response.
[0029]
(3) A specified item whose data update cycle exceeds 1 second In a remote node compatible with wide area communication, if the data update cycle exceeds 1 second, it may be mistaken for an error in IOM operation monitoring. In order to avoid this, if you specify “Yes” for more than 1 second, I / O module operation monitoring will be extended. This prevents a transmission delay from being erroneously determined as an I / O module abnormality.
[0030]
【The invention's effect】
As is clear from the above description, the following effects can be expected according to the present invention.
(1) Since remote nodes can be distributed and arranged at remote locations at arbitrary distances using an existing wide area communication network without adopting a configuration in which FCSs are distributed and connected by connecting control buses over a wide area as in the past, cost is reduced. The effect is great. In addition, cooperation between applications becomes smooth.
[0031]
(2) The function block of the remote node and the interface of field device input / output data are the same as the conventional one, and it is not necessary to be aware of wide area connection when building an application.
(3) Duplexing of the ER bus is also possible.
[0032]
(4) Since the communication with the next node is completed at the same time as the communication with the immediately preceding remote node is completed, even if the no-response monitoring time is set to the worst value of the transmission delay time, the maximum obtained in the wide area communication network Data can be updated at speed.
[Brief description of the drawings]
FIG. 1 is a functional block diagram illustrating an extended connection mode of a remote node in a distributed control device to which the present invention is applied.
FIG. 2 is a functional block diagram illustrating an extended connection mode of a remote node according to the prior art in a distributed control device.
[Explanation of symbols]
1 Host device 2 Control bus 3 FCS
4 I / O bus 5 Local node 11 ER bus 12 Remote node 13 Relay means 17 Wide area network 18, 19 Router 20, 21 Router 22, 23 Hub

Claims (5)

In a distributed control device comprising a host device and a field control station that communicates with the host device via a control bus,
A local node connected to the field control station via an I / O bus;
One or a plurality of remote nodes connected to the local node via a wide area network,
A distribution wherein the remote node self-diagnosis cycle can be set to a setting that exceeds the self-diagnosis cycle of the local node by a user setting when the remote node self-diagnosis is executed by monitoring a data update cycle. Mold control device. The wide area network is realized by a dedicated line service network,
The distributed control apparatus according to claim 1. The wide area network is realized by a wireless LAN;
The distributed control apparatus according to claim 1. When there is no response beyond the no-response monitoring time from the start of communication from the local node to the remote node, it is determined that there is no response, and communication is started to the next remote node,
The distributed control device according to claim 1. The number of non-responses to the communication from the local node to the remote node exceeds the number of no-response attempts, and the remote node is determined to be in an abnormal state when continuously responding,
The distributed control apparatus according to claim 4.

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