JP2003152746A - Distribution type controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a distribution type controller with a function capable of freely connecting a local node to a remote node without restriction of extended distance of a bus by a relay means such as an optical repeater and without a hindrance of physical installation. SOLUTION: The distribution controller comprising a host device and a field control station making communication with the host device via a control bus, is provided with: a local node connected to the field control station via an I/O bus; and one or more remote nodes connected to the local node via a broad area line network.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a field control station (hereinafter FC) in a distributed control device.
The present invention relates to a function that enables a local node connected to S) to be easily connected to a remote node at a remote place, which is extendedly connected via a communication module, via a general router or gateway.

[0002]

2. Description of the Related Art An extended connection mode of a remote node according to a conventional technique in a distributed controller will be described with reference to FIG. 1 is a human interface station (hereinafter referred to as HIS), which is a higher-level device, and 3 is H via a control bus 2.
It is an FCS that communicates with IS1. 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.

If necessary, the control bus 2 is extended to another control bus 7 at a remote place through an appropriate communication means 6, and the FCS 8, the I / O bus 9 and the local node 1 are connected to this control bus.
0 is similarly connected.

In the local node 5, the PSU is a power supply module and the plurality of module IOMs are interface modules for communicating with field devices. The two modules SB401 are FC via the I / O bus 4.
It is a communication module that communicates with S and is duplicated.

The two modules EB401 are ER buses (10 Mbps Ethernet (registered trademark) (10Base2))
Communication module EB of remote node 12 via 11
It is a communication module connected to 501 and is duplicated. The ER 11 can be extended up to about 2 km by the relay means 13 such as an optical repeater. Similarly, 14 is a non-redundant ER bus and is connected to another remote node 15. 16 is ER bus 14
It is a relay means for extension inserted in.

These remote nodes 12 and 15 also have a plurality of input / output interface modules IOM for communicating with the power supply module PSU and field devices, like the local node 5. The communication module EB401 of the local node collects (sets) the field input / output information via the ER buses 11 and 13, and can refer to it from the FCS3.

[0007]

The extension distance of the ER bus can be extended up to a maximum of 2 km by a repeater such as an optical repeater. However, when the distance to the remote node exceeds 2 km or when the physical distance of the ER bus is physically increased, If it could not be installed, the remote node could not be used.

An object of the present invention is to provide a distributed control device having a function of freely connecting a remote node without restriction of a bus extension distance by a relay means such as an optical repeater and without physical obstacles. It is to be realized.

[0009]

In order to achieve the above-mentioned object, a feature of the invention according to claim 1 of the present invention is that a field control station for communicating with a host device and the host device via a control bus. And 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. And, it is equipped with.

A second aspect of the present invention is that the wide area line network is realized by a dedicated line service network.

A third aspect of the present invention is that the wide area network is realized by a wireless LAN.

According to a fourth aspect of the present invention, when there is no response from the start of communication from the local node to the remote node for a period of no response monitoring, it is determined that there is no response and the next remote node is sent. The point is to start communication.

A fifth aspect of the present invention is characterized in that when the number of non-responses to the communication from the local node to the remote node exceeds the number of non-response attempts and there is continuous no response, the remote node is There is a point to judge that it is an abnormal state.

According to a sixth aspect of the present invention, when the self-diagnosis of the remote node is executed by monitoring the data update cycle, the self-diagnosis cycle can be set by the user to select a setting exceeding a predetermined time. .

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a functional block diagram for explaining the configuration of a distributed control apparatus to which the present invention is applied. The same elements as those of the conventional apparatus described in FIG.

The feature of the present invention is that the local node 5 and the remote node 12 are connected to the ER bus 11 and the wide area network 17.
It is in a configuration connected through. Reference numerals 17 and 18 are routers for connecting the duplicated ER bus to the wide area network 17.
Reference numerals 20 and 21 are similar routers, and the communication modules of the remote node and the wide area network 17 are connected via the hubs 22 and 23.
Connect. Although a router is used in the embodiment,
A relay device other than this, for example, a gateway or the like may be used.

The communication module EB402 for communicating with the ER bus 11 in the local node 5 is a communication module dedicated to wide area connection and having the same function as the communication module EB401 in FIG.

The ER bus is 10 Mbps Ethernet (registered trademark) (10Base2) as described above (Et).
HERNET (registered trademark) is a registered trademark and uses TCP / IP protocol for communication on the line. Therefore, it is possible to easily connect to a general router or gateway commercially available from the network equipment manufacturer.

Further, some of these routers and gateways are compatible with a wide area network and wireless, so E
By relaying the R bus with these devices, it is possible to realize distance extension and non-contact type communication.

On the other hand, the transmission speed of the ER bus is 10 Mbps
On the other hand, 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 or the setting contents can be changed for the status management and status setting / collection of field devices connected to the remote node IOM. It is necessary to take measures such as doing.

The wide area line network 17 is a dedicated line service network, and is intended for high-speed digital line services (64k to 6Mbps) and frame relay services (64k to 6Mbps). This wide area network can be replaced with another relay function such as a wireless LAN.

Next, the measures taken when introducing the wide area line network of the present invention to various functions implemented in the prior art will be described. (1) IOM start-up procedure Time-up monitoring In the IOM start-up procedure at the time of initial startup, each step until the start-up is time-monitored, and when the monitoring time is exceeded, it is determined that there is an IOM abnormality. Regarding the IOM startup procedure time-up monitoring time when a wide area network is introduced, the monitoring time of the IOM belonging to the wide area compatible remote node is extended.

(2) Bypass of Module Status Register Monitoring at IOM Rise In some cases, the value of the module status register of the IOM may become indefinite immediately after the IOM is activated, during which 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.

(3) ER bus communication module (EB40
2) Control right switching condition monitoring Regarding the redundant communication module EB402,
The operation states of the connected remote nodes are collected for each EB 402. The operating statuses collected by each communication module are compared, and the remote node status collected by the communication module on the control side is worse than the remote node status collected by the communication module on the standby side. If it is, the communication module control / standby is switched. For the duplicated communication module, the control right switching condition monitoring time is extended.

(4) Monitoring the control right acquisition time of the duplicated IOM With respect to the duplicated IOM, the time until one of the two IOMs becomes the control side is monitored. If there is no IOM to be controlled beyond this time, it is determined that the IOM is abnormal. For the duplicated IOM installed in the wide area compatible remote node, the control right acquisition time of the duplicated IOM is extended.

(5) Self-Diagnosis One-Second Rule In the operation monitoring of the IOM, the rule is that the self-diagnosis is normal when the data update period is within one second. For the IOM installed in the remote node, the self-diagnosis 1 second rule of this data update period is extended.

Further, the characteristic measures 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 the maximum with the accuracy of no-response monitoring time msec. After the communication module EB402 of the local node 5 starts transmission, if the non-response monitoring time is exceeded, it is determined that the communication is non-response, and communication is started to the next remote node. The non-response monitoring time is set to a value exceeding the response time considered to be the limit in the network system. By making it possible to flexibly set this value, it is possible to connect to wide-area remote nodes of all types.

(2) Number of retries at the time of no response When the remote node exceeds the number of retries and does not respond continuously, the communication module EB402 determines the state of the node as FAIL (abnormal state). It is necessary to set the no-response retry count so that the node does not fail due to a transient abnormality (packet loss, data error, response time exceeding the assumption, etc.) on the communication path. 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 at no response.

(3) Specified item whose data update cycle exceeds 1 second In a remote node compatible with wide area communication, the data update cycle is 1
If it exceeds the second, the IOM operation monitoring may be mistaken for an error. To avoid this, if you specify "existence" for more than 1 second, the operation monitoring of the I / O module will be extended. This reduces the transmission delay to I / O.
I try not to misjudge it as a module error.

[0030]

As is apparent from the above description,
According to the present invention, the following effects can be expected. (1) Cost can be reduced because remote nodes can be distributed and distributed at arbitrary distances using an existing wide area communication network without taking the form of connecting FCSs by distributed connection of control buses as in the past. The effect is great. In addition, cooperation between applications becomes smooth.

(2) The function block of the remote node and the interface of the field device input / output data are the same as the conventional ones, and it is not necessary to be aware of the wide area connection in the construction of the application. (3) The ER bus can be duplicated.

(4) Since the communication with the next node is performed 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 wide area communication network concerned Data can be updated at the maximum speed that can be obtained.

[Brief description of 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 has been applied.

FIG. 2 is a functional block diagram illustrating an extended connection mode of a remote node according to a conventional technique in a distributed control device.

[Explanation of symbols]

1 Upper device 2 control bus 3 FCS 4 I / O bus 5 local node 11 ER bus 12 remote nodes 13 Relay means 17 Wide area network 18, 19 Router 20, 21 router 22, 23 hubs

Claims (6)

[Claims] 1. A distributed control device comprising a host device and a field control station communicating with the host device via a control bus, wherein a local node connected to the field control station and the field control station via an I / O bus. And connected to this local node via a wide area network 1
A distributed control device comprising one or a plurality of remote nodes. 2. The distributed control device according to claim 1, wherein the wide area line network is realized by a dedicated line service network. 3. The distributed control apparatus according to claim 1, wherein the wide area network is realized by a wireless LAN. 4. When there is no response from the start of communication from the local node to the remote node over the no-response monitoring time, it is determined that there is no response and communication is started to the next remote node. The distributed control device according to any one of claims 1 to 3, which is characterized. 5. The remote node is judged to be in an abnormal state when the number of non-responses to the communication from the local node to the remote node exceeds the number of non-response attempts and continuously does not respond. The distributed control device according to claim 4, which is characterized in that: 6. The method according to claim 1, wherein when the self-diagnosis of the remote node is executed by monitoring a data update cycle, the self-diagnosis cycle can be set to a value exceeding a predetermined time by user setting. The distributed control device described.