JPH0454097A - Remote supervisory system - Google Patents

Abstract

PURPOSE:To suppress the reduction immediately after collection of monitor information by using the contention system so as to collect monitor information at a fast speed in the normal state when frequency of occurrence of alarm is low and selecting the polling system from the contention system when the frequency of occurrence of alarm is high. CONSTITUTION:Since alarm detected by each slave supervisory device is less in the normal state, the signal collision on a common transmission line 3 is very less. When lots of alarm signals are caused, the signal collision on the common transmission line 2 is increased. A collision detection circuit 7 of a master supervisory device 1 detects collision of a monitor information signal on the common transmission line 3 caused in the contention system, then collision notice from the collision detection circuit 7 is counted and when the count exceeds a specific count within a prescribed time, a switching signal to select the polling transmission control system is sent to changeover circuits 6a, 6b. The changeover circuit 6 selects the polling system transmission control circuit 4 from the contention system transmission control circuit 5 accordingly.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a remote monitoring system, and particularly to a remote monitoring system that normally collects monitoring information using a contention method, and when alarms occur frequently, collects monitoring information using a polling method for a certain period of time. Regarding the system.

[Prior Art] Conventionally, in this type of remote monitoring system, a transmission control procedure for collecting monitoring information has been performed using a polling method or an independent transmission control procedure using only a contention method.

[Problem to be solved by the invention]

In the conventional remote monitoring system described above, the transmission control method for collecting monitoring information was a polling method or only a contention method, so the transmission control method was performed using a single transmission control procedure. When the number of alarms is small, monitoring information can be collected quickly even if there are a large number of subordinate monitoring devices, but when alarms occur frequently and exceed a certain number, signal collisions on the common transmission path increase rapidly. However, with the polling method, even if alarms occur frequently, the speed at which monitoring information is collected does not drop drastically; Since the speed at which monitoring information is collected slows down approximately in proportion to the number of slave monitoring devices, there is a problem in that when there are many slave monitoring devices, the speed at which monitoring information is collected becomes slow even when the alarm frequency is low.

SUMMARY OF THE INVENTION An object of the present invention is to provide a remote monitoring system that can solve the above problems and suppress a decrease in monitoring information collection speed.

[Means to solve the problem]

The remote monitoring system of the present invention is a remote monitoring system that collects monitoring information from a plurality of slave monitoring devices to a main monitoring device using a common transmission path, in which the main monitoring device (A) performs a polling-based transmission control procedure. (B) main monitoring device side contention method transmission control means for controlling the contention method transmission control procedure; (C) main monitoring device side polling method transmission control means; main monitoring device side switching means for switching the contention method transmission control means on the main monitoring device side; (D) collision detection means for detecting a signal collision on the common transmission path during the contention method and outputting a collision signal; (E) a first switching signal for counting the collision signals and switching the transmission control method from the contention method to the polling method when the frequency of collisions becomes higher than a predetermined frequency; switching control means for outputting a second switching signal for returning the transmission control method from the polling method to the contention method after a certain period of time; (F) the first switching signal and the second switching signal; switching signal sending means for sending a signal to the common transmission path, the slave monitoring device comprising: (G) polling method transmission control means on the slave monitoring device side for controlling a polling method transmission control procedure; (H) a controller; a slave monitoring device side contention type transmission control means for controlling a tension type transmission control procedure; (I) a slave monitoring device for switching between the slave monitoring device side polling type transmission control means and the slave monitoring device side contention type transmission control means; side switching means; (J) switching signal receiving means for controlling the slave monitoring device switching means in response to a switching signal transmitted from the main monitoring device via the common transmission path;

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

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

The remote monitoring system shown in FIG. 1 includes a slave monitoring device 2 that collects monitoring information from devices to be monitored, etc., which is connected to the slave monitoring device 2 via a common transmission path 3, and collects monitoring information from the slave monitoring device 2. It consists of a main monitoring device 1.

The main monitoring device 1 also includes a polling type transmission control circuit 4.
, contention type transmission control circuit 5, polling type transmission control circuit 4, and contention type transmission control circuit 5
A switching circuit 8a that switches.

a collision detection circuit 7 that detects a signal collision on the common transmission path 3 and outputs a collision signal during the 6b1 contention method;
When the number of collision signals is counted and the frequency of collisions exceeds a predetermined frequency, a switching signal is output to switch the transmission control method from the contention method to the polling method, and after a certain period of time, the transmission control method is switched again. It is comprised of a switching control circuit 8 that sends out a switching signal for returning from the polling system to the contention system, a switching signal sending circuit 9 that sends the switching signal to the common transmission line 3, and a main monitoring logic circuit 10.

Further, the slave monitoring device 2 includes a polling type transmission control circuit 1.
3. Contention type transmission control circuit 14, boring type transmission control circuit 13, and switching circuit 12a, 12 b1 for switching between contention type transmission control circuit 14 and contention type transmission control circuit 14. The switching signal receiving circuit 11 is configured to control the switching circuits 12a and 12b according to the switching signal received by the user, and a slave monitoring logic circuit 15.

Next, the operation will be explained.

The main monitoring device 1 collects monitoring information from the sub-monitoring device 2 and a plurality of sub-monitoring devices (not shown) having the same configuration as the sub-monitoring device 2 via the common transmission path 3. Here, the explanation will be given using the slave monitoring device 2, but the operation is the same for other slave monitoring devices.

Normally, the switching circuit 6 of the main monitoring device 1 and the switching circuit 12 of the slave monitoring device 2 are connected to the contention type transmission control circuit 5 and the contention type transmission control circuit 4, respectively, as shown in FIG. has been done. In this state, when the slave monitoring logic circuit 15 of the slave monitoring device 2 detects an alarm, the alarm is sent to the main monitoring device as monitoring information via the common transmission line 3 from the contention method transmission control circuit 14 by the contention method. The signal is transmitted to the contention type transmission control circuit 5 and input to the main monitoring logic circuit 10.

At this time, in the normal state, since the number of alarms detected by each slave monitoring device is small, signal collisions on the common transmission path 3 are extremely rare. When alarms occur frequently, the number of signal collisions on the common transmission path 3 increases. When the collision detection circuit 7 of the main monitoring device 1 detects a collision of monitoring information signals on the common transmission path 3 that occurs during the contention method, it notifies the switching control circuit 8 of the collision. The switching control circuit 8 counts the number of collision notifications from the collision detection circuit 7, and when a predetermined number of collision notifications is exceeded within a certain period of time, sends a switching signal to the switching circuit 6 to switch the transmission control method to the polling method. In response, the switching circuit 6 switches from the contention type transmission control circuit 5 to the polling type transmission control circuit 4 side. At the same time, the switching signal is transmitted from the switching signal sending circuit 9 to each slave monitoring device via the common transmission line 3. In the slave monitoring device 2, when the switching signal receiving circuit 11 receives the switching signal and detects that the information is a switching command to the polling method side, the switching circuit 12 switches to the polling method transmission control circuit 13 side. In this way, the polling type transmission control circuit is selected in both the main monitoring device 1 and each slave monitoring device.

Here, the polling type transmission control circuit 4 of the main monitoring device 1
sequentially sends polling signals for each slave monitoring device to the common transmission line 3. When the polling method transmission control circuit 13 of the slave monitoring device 2 receives a polling signal addressed to its own station,
The monitoring information of the slave monitoring logic circuit 15 is sent from the polling type transmission control circuit 13 to the main monitoring device 1 on the common transmission line 3 by a polling method. In the main monitoring device 1 , monitoring information transmitted from the slave monitoring device 2 via the common transmission path 3 is received by the polling type transmission control circuit 4 and transmitted to the main monitoring logic circuit 10 .

When a predetermined period of time has elapsed, the switching control circuit 8 of the main monitoring device 1 outputs a switching signal for switching the transmission control method to the contention method to the switching circuit 6 and the switching signal sending circuit 9. In response, the switching circuit 6 switches from the polling type transmission control circuit 4 side to the contention type transmission control circuit 5 side. At the same time, the switching signal is
The signal is transmitted from the switching signal sending circuit 9 to each slave monitoring device via the common transmission line 3. In the slave monitoring device 2, the switching signal receiving circuit 11 receives the switching signal, and when the information detects a switch that is a switching command to the contention method side, the switching circuit 12 switches to the contention method transmission control circuit 14 side. Change.

In this way, the contention type transmission control circuit is selected in both the main monitoring device 1 and each slave monitoring device, and the collection of monitoring information is performed again using the contention type.

At this point, if the situation of frequent alarms is such that signal collisions occur frequently on the common transmission path 3, the polling method is switched again according to the above-described procedure, and monitoring information is collected. On the other hand, if alarms are not occurring frequently and there are few signal collisions on the common transmission path 3, monitoring information will be collected using the contention method as long as the situation continues.

〔Effect of the invention〕

As explained above, the present invention collects monitoring information at high speed using the contention method in a normal state where the alarm frequency is low, and switches from the contention method to the poll link method in a state where the alarm frequency is high. This has the effect of suppressing a decrease in monitoring information collection speed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Main monitoring device, 2...Slave monitoring device, 3...Common transmission path, 4...Polling type transmission control circuit, 5... ...Contention type transmission control circuit, 6a, 8b...Switching circuit, 7
...Collision detection circuit, 8...Switching control circuit, 9...Switching signal sending circuit, 10...
- Main monitoring logic circuit, 11... Switching signal receiving circuit N 12a, 12b... Switching circuit, 13...
...Polling type transmission control circuit, 14...
Contention type transmission control circuit, 15...Slave monitoring logic circuit.

Claims (1)

[Claims] 1. In a remote monitoring system in which monitoring information is collected from a plurality of slave monitoring devices to a main monitoring device using a common transmission path, the main monitoring device (A) performs a polling-based transmission control procedure. (B) main monitoring device side polling method transmission control means for controlling the contention method transmission control procedure; (C) main monitoring device side polling method transmission control means; main monitoring device side switching means for switching the contention method transmission control means on the main monitoring device side; (D) collision detection means for detecting a signal collision on the common transmission path during the contention method and outputting a collision signal; (E) a first switching signal for counting the collision signals and switching the transmission control method from the contention method to the polling method when the frequency of collisions becomes higher than a predetermined frequency; switching control means for outputting a second switching signal for returning the transmission control method from the polling method to the contention method after a certain period of time; (F) the first switching signal and the second switching signal; switching signal sending means for sending a signal to the common transmission path, the slave monitoring device comprising: (G) polling method transmission control means on the slave monitoring device side for controlling a polling method transmission control procedure; (H) a controller; a slave monitoring device side contention type transmission control means for controlling a tension type transmission control procedure; (I) a slave monitoring device for switching between the slave monitoring device side polling type transmission control means and the slave monitoring device side contention type transmission control means; (J) switching signal receiving means for controlling the slave monitoring device switching means in response to a switching signal transmitted from the main monitoring device via the common transmission path; Monitoring system. 2. The remote monitoring system according to claim 1, wherein the switching control means counts the collision signals within a predetermined period of time, and when a predetermined number is reached, the transmission control method is switched to the contention signal. A first switching signal for switching the transmission control method from the polling method to the polling method is output, and after a certain period of time, a second switching signal is output again for switching the transmission control method from the polling method to the contention method. A remote monitoring system.