JPH11108702A - Trend graph display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To display a trend graph having different sampling cycles with good visibility at a high speed by controlling the line width of a straight line based on the change of data between sampling cycles so as to plot a sampling graph. SOLUTION: A control means 51 fetches a sampled data signal 100, performs usual linear plotting if a sampling cycle is not longer than a reference sampling cycle, connects the data of respective sampling cycles and display the result in a display circuit 2. On the other hand, if a sampling cycle is longer than the reference sampling cycle, a line width to be plotted is calculated by a line width arithmetic circuit 5, and the data 'f' and 'g' of respective sampling cycles are connected by a straight line 'h' and displayed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a trend graph display device, and more particularly to a trend graph display device capable of displaying trend graphs having different sampling periods at high speed and with good visibility.

[0002]

2. Description of the Related Art In a conventional distributed control device or the like, a trend graph is displayed on a display device or the like based on data sampled in a plant or the like under control management.

When displaying a plurality of trend graphs on the same screen, a conventional trend graph display device basically displays a trend graph having the same sampling period, for example, as shown in FIG.
Was displayed as shown in FIG.

On the other hand, when a plurality of trend graphs having different sampling periods are displayed on the same screen, a change in the trend graph having a longer sampling period cannot be identified as a smooth change.

For example, as shown in FIG. 8, the sampling period of FIG.
The trend graph shown in the middle “b” is difficult to identify as a smooth change.

Therefore, in the conventional trend graph display device, a long sampling period is spline-interpolated and displayed as a smooth change.

FIG. 9 is a block diagram showing an example of a conventional trend display device for performing such spline interpolation.

In FIG. 9, 1 is a control circuit, 2 is a display circuit, 3 is a storage circuit, 4 is a spline interpolation circuit, and 100 is a data signal sampled in a plant or the like. Further, the control circuit 1 and the spline interpolation circuit 4
0.

The data signal 100 is connected to the control circuit 1, the input and output of the control circuit 1 are mutually connected to the storage circuit 3 and the spline interpolation circuit 4, and the control output of the control circuit 1 is connected to the display circuit 2.

The operation of the conventional example shown in FIG. 9 will now be described with reference to FIG.
This will be described with reference to FIG. FIG. 10 is a flowchart illustrating the operation of the control unit 50.

In FIG. 10A, the control means 50 determines whether or not the display of the trend graph has been completed. If the display of the trend graph has been completed, the processing is terminated.

On the other hand, if the display is not completed, in FIG. 10B, the control means 50 determines whether or not the sampling cycle is longer than the reference sampling cycle.

In FIG. 10B, if the sampling cycle is not long, the control means 50 performs a normal linear plot in FIG. 10C and returns to the processing of FIG. 10A.

For example, the control seeding means 50 is shown in FIG.
As shown in "a", data "b", "c" and "d" in FIG. 10 which are data for each sampling period are connected by a straight line and displayed.

If the sampling period is longer than the reference sampling period in FIG. 10B, the control means 50 performs spline interpolation processing in FIG. 10D and the spline curve in FIG. And returns to the processing of FIG.

For example, the control means 50 operates as shown in FIG.
As shown in FIG.
The middle "f", "g" and "h" are connected by a spline curve and displayed.

The sampling period of the trend graph shown by "e" in FIG. 10 is set to be three times that of the trend graph shown by "a" in FIG.

Here, the spline interpolation means that a linearly approximated curve is calculated based on data signals of several periods before and after the interpolation, and a long sampling period is connected by the linearly approximated curve to realize a smooth change. Is what you do.

As a result, even when a plurality of trend graphs having different sampling periods are displayed on the same screen, a smooth change can be displayed by performing spline interpolation during a long sampling period.

[0020]

However, in spline interpolation, a straight line approximation curve is calculated based on data signals of several cycles before and after the interpolation, so that the processing time is longer than that of a simple straight line plot and the processing time is longer. When updating the trend graph, the processing time becomes a problem. Accordingly, an object of the present invention is to realize a trend graph display device capable of displaying trend graphs having different sampling periods at high speed with good visibility.

[0021]

According to a first aspect of the present invention, there is provided a trend graph display device, comprising: a display circuit for displaying a trend graph; a display circuit for controlling the display circuit; Control means for taking in the data signal, controlling the line width of a straight line based on a change in data between sampling periods, and plotting the trend graph.

In order to achieve the above object, according to a second aspect of the present invention, in the first aspect of the present invention, the control means calculates a line width, and the line width calculating circuit calculates the line width. And a control circuit for plotting the trend graph with the straight line having the line width described above.

In order to achieve the above object, according to a third aspect of the present invention, in the first aspect of the present invention, the line width is increased when the change of data between sampling periods is steep.
The line width is reduced when there is little change in data between sampling periods.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the line width is narrowed when the data change between sampling periods is steep.
When there is little change in data between sampling periods, the line width is widened.

In order to achieve such an object, a fifth aspect of the present invention is characterized in that the fifth aspect of the present invention is used as a display device of a distributed control device in the first to fourth aspects of the present invention.

In order to achieve such an object, the sixth aspect of the present invention is characterized in that the sixth aspect of the present invention is used as a display device of a waveform display device in the first to fourth aspects of the present invention.

In order to achieve the above object, a seventh aspect of the present invention is characterized in that in the sixth aspect of the present invention, the waveform display device is an oscilloscope.

In order to achieve the above object, an eighth aspect of the present invention is characterized in that in the first to fourth aspects of the present invention, it is used as a display device of a waveform recording apparatus.

In order to achieve the above object, a ninth aspect of the present invention is characterized in that in the eighth aspect of the present invention, the waveform display device is a recorder.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 1 is a configuration block diagram showing one embodiment of a trend graph display device according to the present invention.

In FIG. 1, 1, 2, 3 and 100 are the same as in FIG.
Reference numeral 5 denotes the line width calculation circuit. 1 and 5 constitute the control means 51.

The data signal 100 is connected to the control circuit 1, the input and output of the control circuit 1 are mutually connected to the storage circuit 3 and the line width calculation circuit 5, and the control output of the control circuit 1 is connected to the display circuit 2. .

The operation of the embodiment shown in FIG. 1 will now be described with reference to FIG. FIG. 2 is a flowchart illustrating the operation of the control unit 51.

In FIG. 2A, the control means 51 determines whether or not the display of the trend graph is completed. If the display of the trend graph is completed, the process is terminated.

On the other hand, if the display is not completed, the control means 51 in FIG. 2B determines whether or not the sampling cycle is longer than the reference sampling cycle.

In FIG. 2B, if the sampling cycle is not long, the control means 51 performs a normal linear plot in FIG. 2C and returns to the processing of FIG. 2A.

For example, as shown in "A" in FIG. 2, the control means 51 outputs the data for each sampling period in "A" in FIG.
"B", "c" and "d" are displayed by connecting them with a straight line.

If the sampling period is longer than the reference sampling period in FIG. 2B, the control means 51 calculates the line width to be plotted in FIG. The interval between data is plotted by a straight line having the line width, and the process returns to the process of FIG.

For example, as shown in "e" in FIG. 2, the control means 51 outputs data in each sampling cycle as shown in "e" in FIG.
The lines "f" and "g" are connected by a straight line having the line width indicated by "h" in FIG.

Further, the sampling period of the trend graph shown by "e" in FIG. 2 is set to be three times that of the trend graph shown by "a" in FIG.

Here, the method of calculating the line width will be described in detail with reference to FIGS. FIG. 3 is an explanatory diagram showing a specific example plotted by a straight line having a line width, and FIG. 4 is an explanatory diagram for explaining a method of calculating the line width.

As shown in FIG. 3A, the trend graph has a configuration in which parallelograms such as "A", "B", and "C" in FIG. 3 are sequentially connected. "
Sides indicated by "d", "e" and "f" have the same length and are parallel to each other.

The angles of the sides indicated by "d", "e", and "f" in FIG. 3 are, for example, "157.5 degrees (= 157.5 degrees) with respect to the horizontal direction as shown in FIG. 7π / 8) ”or“ −22.5 degrees (= −π / 8) ”.

For this reason, the parallelogram shown in FIG.
When connecting data for each sampling period shown in the middle "g", "h" and "ri", the line width shown in "nu" and "lu" in FIG. 3 changes.

As can be seen from FIG.
When the angles of the sides indicated by "d", "e", and "f" are inclined with respect to the horizontal direction by, for example, "157.5 degrees (= 7π / 8)", the line width becomes large when the data changes steeply. The line width tends to be narrower when the data width is large and the change in data is small.
In other words, a portion where the data changes sharply is highlighted.

Accordingly, the line width calculation circuit 5 calculates the line width from the data for each sampling period and outputs the calculated line width to the control circuit 1. The control circuit 1 plots a parallelogram having this line width.

For example, in FIG. 3, "d", "e" and "f"
Etc., the length of the side shown as “a” and the angle with respect to the horizontal direction as “
α ”, the line widths indicated by“ nu ”and“ ru ”in FIG.
Assuming that the angle connecting the data for each sampling period, such as “g”, “h”, and “li” in FIG. 3, is “β”, as is clear from FIG. 4, (W / 2) / (a / 2) = cos (π / 2−θ−β) (1)

Here, from FIG. 4, “θ = π−α”,
As described above, if “α = 7π / 8”, the equation (1) becomes: W = a · cos {π / 2−β− (π−α)} = a · cos (α−π / 2−β ) = A · cos (7π / 8−π / 2−β) = a · cos (3π / 8−β) (2)

From equation (2), if the angle connecting data at each sampling period is “β = 3π / 8”, the line width is “W”.
= A "and becomes the maximum.

For example, FIG. 5 is a characteristic curve diagram showing an example of a trend graph using such line width interpolation.
5A is a trend graph without line width interpolation, and FIG. 5B is a trend graph with line width interpolation. Also, in FIG.
The sampling period of "c" is eight times the sampling period of "b" and "d" in FIG.

As described above, by using the line width interpolation, the line width of the portion where the change of the data indicated by "e" in FIG. 5 is steep becomes wide, and the change of the data indicated by "f" in FIG. 5 is small. The line width of the portion tends to be narrow, and the visibility is improved even in trend graphs having different sampling periods.

Further, since the above-mentioned spline curve is substantially included in the line width, the trend graph trend can be grasped globally.

Further, the processing time is shortened because the line width is simply calculated as shown in the equation (2) instead of the complicated processing of calculating a linearly approximated curve as in the conventional spline interpolation.

As a result, by using line width interpolation for plotting a trend graph by controlling the line width of a straight line based on a change in data between sampling periods, trend graphs having different sampling periods are displayed at high speed and with good visibility. It becomes possible.

In FIG. 3, the angles of the sides indicated by "d", "e", and "f" in FIG.
Although tilted by 7.5 degrees (= 7π / 8) ", it is also possible to highlight a case where the data change is small by changing this angle.

For example, FIG. 6 is an explanatory view showing another specific example plotted by a straight line having a line width. As shown in FIG. 6A, horizontal sides of sides having the same length and being parallel to each other are shown. If the angle with respect to the direction is "67.5 degrees (= 3π / 8)" or "-112.5 degrees (= 5π / 8)", a trend graph as shown in FIG. 6B is obtained.

As can be seen from FIG.
67.5 degrees (= 3π / 8), the line width of the portion where the change of the data indicated by “a” in FIG.
The line width of the portion where the data change shown in the middle "b" is small tends to be wide. That is, a portion where the data change is small, in other words, a stable portion is highlighted.

In this case, the line width “W ′” is calculated from the equation (2) as “α”
= 3π / 8 ″, W ′ = a · cos {π / 2−β− (π−α)} = a · cos (α−π / 2−β) = a · cos (3π / 8−π / 2−β) = a · cos (−π / 8−β) (3)

From the equation (3), if the angle connecting data at each sampling period is “β = −π / 8”, the line width is “
W ′ = a ″ and becomes the maximum.

The angles of the sides having the same length and being parallel to each other with respect to the horizontal direction are not limited to the above-described specific examples, but may be appropriately adjusted according to the specifications required for the trend graph. It is possible.

In the above description, the distributed control device is taken as an example. However, the present invention is not limited to the distributed control device, but any device that displays waveform information of a waveform display device such as an oscilloscope or a waveform recording device such as a recorder. It can be applied to any of them.

In FIG. 1, the control circuit 1 and the line width calculation circuit 5 are shown separately for simplicity of explanation.
Of course, both functions may be realized in one control circuit.

Although the storage circuit 3 is illustrated in FIG. 1, the storage circuit 3 is not an essential component when it is not necessary to store the trend graph.

[0064]

As is apparent from the above description,
According to the present invention, the following effects can be obtained. A trend graph that can display trend graphs with different sampling periods at high speed and with good visibility by using line width interpolation that plots a trend graph by controlling the line width of a straight line based on changes in data between sampling periods. A display device can be realized.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram showing an embodiment of a trend graph display device according to the present invention.

FIG. 2 is a flowchart illustrating an operation of a control unit.

FIG. 3 is an explanatory diagram showing a specific example plotted with a straight line having a line width.

FIG. 4 is an explanatory diagram illustrating a calculation method of a line width.

FIG. 5 is a characteristic curve diagram showing an example of a trend graph.

FIG. 6 is an explanatory diagram showing another specific example plotted by a straight line having a line width.

FIG. 7 is a characteristic curve diagram showing a trend graph of the same sampling period.

FIG. 8 is a characteristic curve diagram showing a plurality of trend graphs with different sampling periods displayed on the same screen.

FIG. 9 is a configuration block diagram showing an example of a conventional trend display device.

FIG. 10 is a flowchart illustrating the operation of the control means.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Control circuit 2 Display circuit 3 Storage circuit 4 Spline interpolation circuit 5 Line width calculation circuit 50, 51 Control means 100 Data signal

Claims (9)

[Claims] 1. A trend graph display device, comprising: a display circuit for displaying a trend graph, controlling the display circuit, taking in a sampled data signal, and controlling a line width of a straight line based on a change in data between sampling periods. And a control unit for plotting the trend graph. 2. The control means comprises: a line width calculating circuit for calculating the line width; and a control circuit for plotting the trend graph with a straight line of the line width calculated by the line width calculating circuit. The trend graph display device according to claim 1, wherein the trend graph display device is characterized in that: 3. The method according to claim 2, wherein the line width is widened when the data change between sampling periods is sharp, and the line width is narrowed when the data change between sampling periods is small. The trend graph display device according to claim 1. 4. The method according to claim 1, wherein the line width is narrowed when the change in data between sampling periods is sharp, and the line width is widened when the change in data between sampling periods is small. The trend graph display device according to claim 1. 5. The trend graph display device according to claim 1, wherein the trend graph display device is used as a display device of a distributed control device. 6. The trend graph display device according to claim 1, wherein the trend graph display device is used as a display device of a waveform display device. 7. The trend graph display device according to claim 6, wherein said waveform display device is an oscilloscope. 8. The trend graph display device according to claim 1, wherein the trend graph display device is used as a display device of a waveform recording device. 9. The trend graph display device according to claim 8, wherein said waveform display device is a recorder.