JPH0644742B2 - Multiplex transmission system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a multiplex transmission system for wire saving in factories, plants, etc., and more particularly to a function of transmitting an analog signal in the form of a digital signal. Regarding what you have.

[Conventional technology]

An example of this kind of multiplex transmission system is shown in FIG.

That is, in this multiplex transmission system, the master station 2 and a plurality of (two in the illustrated example) slave stations 4a and 4b are connected to each other via a transmission line 6.

The master station 2 and the slave stations 4a and 4b are, for example, H
Transmission control units 21 and 41 for multiplex communication according to the DLC procedure (high-level daylink control procedure) are provided, respectively. In addition, the transmission control unit 21 of the master station 2 also has a master function that controls the entire system. However, unlike this example, it is possible to allow the master function to coexist in any of the slave stations without being made independent as a master station.

The slave station 4a has an input section 42 for input interface and has a function of A / D converting an analog input signal AI into a digital signal DS, and the slave station 4b has an input interface 42 for output interface and digital. An output unit 43 having a function of D / A converting the signal DS into an analog output signal AO is provided.

In the above-mentioned multiplex transmission system, the analog input signal AI input to the slave station 4a is A / D converted there, and once transmitted to the master station 2 in the form of a digital signal DS in accordance with the concentration request from the master station 2. From there, it is delivered in the form of a digital signal DS to the slave station 4b, where it is D / A converted and output as an analog output signal AO.

[Problems to be solved by the invention]

In the conventional multiplex transmission system as described above, the adjusting function of the offset and gain of the analog input / output signals AI and AO in the input section 42 and the output section 43 of the slave stations 4a and 4b is fixed or semi-fixed. Therefore, the analog input signal AI is only output as the analog output signal AO in a state close to unprocessed.

By the way, when incorporating and using it as an actual system, it is often desired to perform correction such as signal compression, expansion, and shift.

For example, when the analog input specification of the input section 42 of the slave station 4a and the analog output specification of the output section 43 of the slave station 4b are both DC0 to 10V, the actual input signal AI changes from DC2 to 7V. When there is only width, when the input signal AI is DC2V, the output signal AO is DC0V
When the input signal AI is DC 7V, the output signal AO is DC
There are cases where it is set to 10V.

In such a case, in the conventional system, the range covered by the offset and gain adjustments described above is naturally limited, and even if an external circuit is added, it can be used only in that specific case. In any case, the range that can be handled was extremely limited.

Therefore, an object of the present invention is to provide a multiplex transmission system capable of correcting data compression, expansion, shift, etc. between analog input signals and output signals.

[Means for solving problems]

The multiplex transmission system of the present invention is a correction means 30 for correcting and outputting the value of the digital signal DS, as shown in FIG. 1, in the middle of the transmission path of the digital signal DS as described above. Lower limit value X of the input signal
₁ , upper limit value X ₂ , lower limit value Y ₁ and upper limit value Y of output signal
Setting means 301 for setting ₂ and the digital signal D
Calculation means 302 for calculating the corrected value Y by performing the calculation of the following equation based on the value X of S before correction and the values X ₁ , X ₂ , Y ₁ and Y ₂ set by the setting means 301. When, And a rounding means 303 for rounding and outputting the value Y.

[Action]

For example, the above equation can be calculated by using two points (X ₁ ,
A straight line L passing through Y ₁ ) and (X ₂ , Y ₂ ) is represented.

Therefore, the value Y output from the calculation unit 302 has a linear relationship with the input value X, and changes when the input value X changes within the range of X _{1 to} X ₂ changes within the range of Y ₁ to Y _2. To do.

Therefore, by setting the above values X ₁ , X ₂ , Y ₁ , and Y ₂ to predetermined values by the setting means, the change width of the output value Y is compressed and expanded with respect to the change width of the input value X. , Can be shifted, etc.

In that case, since the value Y output from the arithmetic means 302 may have a fraction, it is rounded by the rounding means 303, that is, rounded, rounded up, rounded down, etc. Is output to prevent any trouble (mismatch) in the subsequent D / A conversion.

〔Example〕

FIG. 3 is a block diagram showing a multiplex transmission system according to an embodiment of the present invention. The same or corresponding parts as those in FIG. 5 are designated by the same reference numerals, and the differences from the conventional example will be mainly described below.

In this embodiment, the transmission control unit 21 as described above is used.
The above-mentioned correction means 30 is provided in the mask station 20 having

The mask station 20 includes a CPU 203 and a ROM interconnected by a bus 202, as shown in FIG.
A microcomputer 201 having a 204, a RAM 205 and an I / O port 206 is provided.
The communication control unit 2 that follows the above-mentioned HDLC procedure is attached to the O port.
07 and the interface unit 208 are connected.
The transmission line 6 described above is connected to the communication control unit 207, and the setting unit 209 is connected to the interface unit 208.

The microcomputer 201 and the communication control unit 20
7 realizes the function of the transmission control unit 21 described above, and the microcomputer 201, the interface unit 208, and the setting unit 209 realize the function of the correction unit 30 described above.

An example of the overall operation will be described mainly with reference to FIGS. 3 and 4. The lower limit value of the change width to be corrected by the setter 209 of the analog input signal AI input to the slave station 4a. X ₁ , upper limit X ₂ , and slave station 4
The lower limit Y ₁ and the upper limit Y ₂ of the desired change width of the corrected analog output signal AO ′ output from b are set in advance.

The analog input signal AI of the value X input to the slave station 4a is A / D-converted there, and is once sent to the master station 20 in the form of a digital signal DS of the value X according to the concentration request from the master station 20. .

In the master station 20, the correction means 30 therein applies the above-described correction to the value X of the digital signal DS, and the digital signal D having the value Y'as described above.
S'is created and delivered to slave station 4b.

In the slave station 4b, the digital signal DS '
Is D / A converted to an analog output signal AO ′ of value Y ′.
Output as.

Therefore, in such a multiplex transmission system, by setting the values X ₁ , X ₂ , Y ₁ , and Y ₂ variously, data compression and expansion between the analog input signal AI and the output signal AO ′ can be performed. Correction such as shift can be freely performed.

For example, when the analog input specifications of the input section 42 of the slave station 4a and the analog output specification of the output section 43 of the slave station 4b are both DC0 to 10V, the actual change width of the input signal AI is DC2 to DC2. In the case of 7V, the change width of the output signal AO 'is expanded to DC0 to 10V, and conversely, when the change width of the input signal AI is DC0 to 10V, the change width of the output signal AO' is compressed to DC2 to 7V. Alternatively, when the change width of the input signal AI is 0 to 5V DC, the change width of the output signal AO 'can be shifted to 5 to 10V DC.

It is also possible to store the values X ₁ , X ₂ , Y ₁ , and Y ₂ as described above in the plural master stations 20 in advance and change the correction content for each signal collected and distributed by the master station 20. Is.

Further, the correction means 30 as described above does not necessarily mean that the master station 2
It is not necessary to provide it at 0, and if it is in the middle of the transmission path of the digital signal, it may be at another place, for example, the A / D of the slave station 4a
Converted digital signal path or slave station 4b
It may be provided in the path of the digital signal before the D / A conversion of the above.

〔The invention's effect〕

As described above, according to the present invention, it is possible to freely correct the compression, expansion, shift, etc. of the eta between the analog input signal and the output signal. As a result, it is possible to easily and flexibly respond to input signals of various levels, ranges, etc. from the user with the same hardware by simply changing the set value. Therefore, it is possible to realize a multiplex transmission system having a very flexible user interface.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of a correction means in the multiplex transmission system according to the present invention. Figure 2 shows
6 is a graph showing a straight line passing through two points (X ₁ , Y ₁ ) and (X ₂ , Y ₂ ). FIG. 3 is a block diagram showing a multiplex transmission system according to an embodiment of the present invention. FIG. 4 is a block diagram showing a basic configuration example of the master station shown in FIG.
FIG. 5 is a block diagram showing an example of a conventional multiplex transmission system. 2, 20 ... Master station, 4a, 4b ... Slave station, 6
...... Transmission path, 30 …… correction means, 301 …… setting means,
302 ... Arithmetic means, 303 ... Rounding means, AI ... Analog input signal, AO, AO '... Analog output signal, DS, DS' ... Digital signal.

Claims (1)

[Claims] 1. In a multiplex transmission system for transmitting an analog input signal in the form of a digital signal and outputting it as an analog output signal, a value of the digital signal is corrected and output in the middle of a transmission path of the digital signal. Correction means for setting the lower limit value X ₁ and the upper limit value X _{2 of} the input signal, the lower limit value Y ₁ and the upper limit value Y ₂ of the output signal, and the uncorrected value X of the digital signal.
And the values X ₁ , X set by the setting means
Calculating means for calculating the corrected value Y by performing the calculation of the following equation based on ₂ , ₂ , Y ₁ and Y ₂ ; A multiplex transmission system comprising: a rounding unit that rounds and outputs the value Y.