JPH0446494B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a signal multiplexing input circuit for a digital multiplexing transmission system, and in particular to an input circuit for inputting automobile driving operation signals and operating state detection signals to terminal devices of the transmission system. be. [Prior Art] Recently, in order to simplify and reduce the amount of wiring in automobiles, which have become increasingly complex and bloated, a plurality of terminal devices connected to each other by transmission lines are distributed in the vehicle, and each terminal device A digital multiplex transmission device has been developed that inputs signals from local switches and sensors and transmits them to the transmission path, and also receives and processes information sent by other terminal devices and outputs it to local electrical equipment. There is. The input signals of such a digital multiplex transmission device include a cooling temperature sensor,
There are analog signals that are input from the remaining fuel level sensor, instrument lighting controller, etc., and open/close signals that are input from switches operated by the driver and sensors that detect the operating state of the vehicle in binary terms. Conventionally, technologies related to input circuits that input analog signals and open/close signals as described above to terminal devices include Oki Electric Research and Development, 45

[45] No. 2 (Showa 54-
3), P61, and those described in Figure 8. FIG. 2 is a block diagram showing an example of an input circuit configuration conventionally used in a terminal device that collects these analog signals and switching signals.
In FIG. 2, 1 is a terminal device installed in the vehicle, 2 and 3 are analog sensors such as thermistors provided for measuring the temperature of cooling water, and 4 and 5 are analog sensors that convert signals from the analog sensors into electrical potentials. Connect one end to a DC power supply in order to convert the change in
A resistor connected to Vs, 6 a multiplexer that selects one signal from a plurality of analog input signals, 7 a selection control signal that specifies input signal selection for the multiplexer 6, 8 A/D conversion 9 is a bus line, 10 is a microprocessor, 11 to 14 are contacts for open/close signals that exist only in either OFF or ON state, such as switches operated by passengers, and 15 to 18 are respective contacts. A resistor 19 for converting open/close signals into voltage changes receives the open/close signal group in parallel and connects the bus line 9
This is an open/close signal input circuit that can send the data to the user. In order for the microprocessor 10 to read the analog signal, the microprocessor 1
0 sends the selection control signal 7 to the multiplexer 6 through the bus line 9 to select the desired analog signal input, and then sends a command to the A/D conversion circuit 8 to select the analog signal selected by the multiplexer 6. Digitize and read the data via bus line 9. When reading open/close signals, these open/close signals are always given to the open/close signal input circuit 19, and the microprocessor 10
commands the open/close signal input circuit 19, the open/close signal input circuit 19
The states of the close signals 11 to 14 are each independently sent out in correspondence with the data bits in the bus line 9, and the microprocessor 10 reads them. As explained above, conventionally, when inputting various signals into the terminal device 1, a method has been used in which an analog signal input system and an open/close signal input system are provided separately. [Problems to be Solved by the Invention] However, when configuring the input circuit in the terminal device 1 as described above, many commercially available integrated circuits used as the multiplexer 6 have eight signal input channels; Actually, the number of analog signals that one terminal device should input from a vehicle almost never exceeds two points. In other words, the analog signal measurement capability is not used effectively enough, resulting in a redundant device. The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a signal multiplexing input circuit that eliminates the above-mentioned problems and contributes to circuit simplification, device miniaturization, and cost reduction. [Means for Solving the Problems] In order to solve the above problems, the present invention provides an input circuit that collects at least one analog signal and a plurality of open/close contact signals via a signal line. Divide the open/close contacts of each adjacent contact into multiple groups, and generate a composite signal by combining the open/close signals from the groups for each group and in the vicinity of the group via weighting resistors. a weighted synthesis circuit that connects the synthesized signal and the analog signal to each channel input terminal to select an arbitrary channel; and an A/D conversion circuit that converts the output of the multiplexer into digital data. is provided, and the digitized composite signal from the A/D conversion circuit is inversely converted in accordance with the weighted synthesis rules of the weighted synthesis circuit to determine each state of the open/closed signal. [Function] By configuring the signal multiplexing input circuit as described above, the open/close signal is passed through the synthesis circuit to fill the unused analog signal input circuit of the terminal device, which is conventionally left unused as a redundant circuit. Since it is input to the used part, the analog signal input circuit can be used effectively, and since a plurality of multiplexed open/close signals can be received with one analog signal input system, an input circuit dedicated to open/close signals can be eliminated. In addition, as described above, multiple open/close contacts are divided into multiple groups and a weighted synthesis circuit is provided for each group, so the number of combinations of open/close signals connected to one weighted synthesis circuit is reduced. , the difference in output voltage between each combination can be increased, and the state of the open/close signal can be determined without the need for a high-grade voltage measurement circuit. In addition, multiple open/close contacts are divided into multiple groups for each adjacent contact, and a weighting synthesis circuit is provided for each group and in the vicinity of the group, and this synthesis circuit and a multiplexer circuit are connected using a single signal line. Since the structure is connected, the number of wires can be kept to the necessary minimum. [Example] An example of the present invention will be described below based on the drawings. FIG. 1 is a block diagram showing the configuration of a signal multiplexing input circuit according to a first embodiment of the present invention. In this figure, parts with the same reference numerals as those in FIG. 2 indicate the same or corresponding parts (hereinafter, the same applies to other figures). As shown in the figure, the terminal device is provided with a plurality of weighting synthesis circuits 25...26, and on the input side of the weighting synthesis circuits 25...26, contacts 11 to 14 for open/close signals are arranged in units of three contacts. Group and connect, weighting synthesis circuits 25...26
The output side of is connected to the input terminal of multiplexer 6. Now, in order to check the states of the contacts 11 to 13 of the open/close signal, the microprocessor 10 selects the input channel of the multiplexer 6 to which the output of the weighting synthesis circuit 25 is connected, using the selection control signal 7. The digital data specified and measured by the A/D conversion circuit 8 is read through the bus line 9, and the opening/closing at that point is performed by inversely converting the data according to the synthesis rules described later. Determine the signal status. The same operation can be performed for other systems of weighting and combining circuits 26 by appropriately manipulating the selection control signal 7 of the multiplexer 6. Furthermore, with regard to measuring the signals from the analog sensors 2 and 3, there is no difference in circuit configuration and operation from that described in connection with the conventional circuit shown in FIG. 2. The weighting synthesis circuits 25...26 and the inverse transformation of the synthesis rules will be explained below. FIG. 3 shows the weighting synthesis circuits 25...2 of FIG.
6 is a circuit diagram showing a circuit configuration of one of the circuits of FIG. In the figure, 11 to 14 are the open/close signal contacts mentioned in the explanation of FIG. The weighting resistor 24 is a series voltage dividing resistor inserted between the collective connection point of the weighting resistor and the DC power supply Vs, and Vt is the output terminal voltage of the weighting synthesis circuit. In FIG. 3, weighting resistors 20, 21,
The resistance values of 22 and 23 are respectively R/2 ⁰ , R/2 ¹ , 2/2 ²
, ..., R/2 ⁿ , If the resistance value of the voltage dividing series resistor 24 is Rs, the output terminal voltage Vt for the states of the contacts 11 to 14 of the open/close signal is expressed by the following equation. Vt=Vs/1+Rs/R(2 ⁰・b ₀ +2′・b ₁ +2 ²・b
₂ +…+2 _o・b _o )…(1) Here, n is the number of open/close signals minus 1, and b ₀ , b ₁ , b ₂ ,…, b _o are the open/close signals. /Closed signals 11, 12, 13, . . . , 14 each take a value of 1 when the state is closed, and a value of 0 when the state is open. Figure 4 is a graphical representation of this formula.
The open/close signal status b ₀ ~ b _o combination is 000...0,
100…0,010…0,~,011~1,111…1, the output terminal voltage of the weighting synthesis circuit
It shows how Vt becomes V ₀ , V ₁ , V ₂ , ~, V _(2o+1-2) , V _(2o+1-1) . As is clear from this figure, for every combination of open/close signals, all different output terminal voltages
Vt is determined. Conversely, pre-weighting resistor 2
When the resistance values of 0 to 23, the voltage dividing resistor 24, and the value of the DC power supply voltage Vs are known, if the output terminal voltage Vt of the weighting synthesis circuit is measured, the current open /
The state of the closed signal can be determined from equation (1) above. However, in reality, when the number of open/close signals (n+1) connected to one composite circuit is increased, the difference between the output terminal voltages of other adjacent combinations becomes smaller, and it is difficult to determine the correct contact state. is difficult to realize because it requires a high-grade voltage measurement circuit. As can be seen from Figure 4,
This characteristic is most pronounced in regions with a large number of closed contacts. In the embodiment shown in FIG. 1, taking this into consideration, the contacts 11 to 14 for open/close signals are grouped into groups of three contacts, and each weighting circuit 25...26
connected to. In the first embodiment shown in FIG. 1, the weighting synthesis circuits 25...26 are constructed inside the terminal device 1, but as shown in FIG. 5 as a second embodiment,
If weighting resistors 20 to 22 can be added to the operating switches and binary sensors 11 to 13, these operating switches and binary sensors 11
The resistors 20 to 22 connected to the resistors 20 to 13 can be successively connected to each other at the mounting part, and this can be connected to the terminal device 1 with a single signal line 27.
Wiring can be simplified. In this case, the terminal device 1 side has a built-in voltage dividing resistor 24, and in order to measure the output terminal voltage,
The configuration after inputting to the multiplexer 6 is exactly the same as that shown in FIG. [Effects of the Invention] As explained above, according to the present invention, the following excellent effects can be obtained. (1) Since the open/close signal is connected to the input terminal to which the analog signal of the multiplexer circuit is not connected via the weighted synthesis circuit, the analog function of the input circuit can be effectively used, and multiple open/close signals can be connected. Since the contacts are divided into a plurality of groups for each adjacent contact, a weighting synthesis circuit is connected for each group and in the vicinity of the group, and this synthesis circuit and a multiplexer circuit are connected by a single signal line. The number of wiring lines can be kept to the minimum necessary, making it possible to downsize, simplify, and lower the cost of the device. (2) In addition, as described above, multiple open/close contacts are divided into multiple groups and a weighted synthesis circuit is provided for each group, so the number of combinations of open/close signals connected to one weighted synthesis circuit is is reduced, the difference in output voltage between each combination can be increased, and the state of the open/closed signal can be determined without the need for a high-grade voltage measurement circuit.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a signal multiplexing input circuit according to the first embodiment of the present invention, FIG. 2 is a block diagram showing an example of the configuration of a conventional input circuit, and FIG. 3 is a block diagram showing a configuration example of a conventional input circuit. A circuit diagram showing the configuration, FIG. 4 is a diagram showing the output terminal voltage characteristics of the weighting synthesis circuit,
FIG. 5 is a circuit diagram showing a modification of the weighting and combining circuit of the signal multiplexing input circuit according to the second embodiment of the present invention. In the figure, 1... terminal device, 2, 3... analog sensor, 4, 5... resistor, 6... multiplexer, 7...
Selection control signal, 8... A/D conversion circuit, 9... Bus line, 10... Microprocessor, 11-14...
Open/close signal contact, 15-18...Resistor, 24...
Voltage dividing resistor, 25, 26... weighting synthesis circuit.

Claims (1)

[Claims] 1. In an input circuit that collects at least one or more analog signal and a plurality of open/close contact signals via a signal line, the plurality of open/close contacts are connected to each other for each adjacent contact. a weighted synthesis circuit that divides into groups and generates a synthesized signal by synthesizing open/close signals from the group via weighting resistors for each group and in the vicinity of the group; the synthesized signal and the analog signal; A multiplexer circuit that can select any channel by connecting it to each channel input terminal, an A/D converter circuit that converts the output of the multiplexer into digital data, and a digital converter circuit that converts the output of the multiplexer into digital data. A signal multiplexing input circuit comprising a processing device that performs processing such as inversely transforming the composite signal in accordance with the weighting composition rule of the weighting composition circuit and determining each state of the open/closed signal.