JPH073698Y2 - A / D converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a terminal device used in a system or the like for controlling signals transmitted and received to and from controlled devices dispersed at a plurality of points. A / D converter

[Prior Art] As the above-mentioned terminal device, there is a device in which the number of analog signals that can be input by one device has been reduced. However, in the same installation place of this terminal device, an analog signal for connecting and inputting a large number of devices If there are many cases, a plurality of terminal devices will be used, which will increase the cost of the entire system. On the other hand, there is a multipoint input terminal device capable of inputting a large number of analog signals with one terminal device.

FIG. 4 shows an example of a system in which this type of terminal device is used. As shown in FIG. 5, the system shown in FIG.
Each center unit C cyclically polls each terminal unit T with a different address for each terminal unit. On the other hand, when each polling address matches the address of this terminal unit, that is, this terminal unit When the analog input signal fetched from the controlled device connected to the unit matches the address to which it is assigned, the A / D converted data is sent to the center unit C.

The address setting in the above-mentioned terminal unit will be described in detail. Allocation of analog input signals to be taken in by a terminal unit The setting range of addresses is 256 from 00H to FFH, and if one address is assigned to one amount of analog input signals, for example,
When the quantity is 16, the maximum number of terminal units that can be installed in the system is 16.

In this case, for example, 00H, 01H, 02H ..., 0FH is used as the address of the analog signal to be taken in by one terminal unit, and the allocation address of the next terminal unit is set to 10H, 11H, 12H, ..., 1FH in order. can do.

In such a configuration, for example, the terminal unit to which the address 00H is assigned sends the A / D conversion data when the polling address of the center unit C is 00H, 01H, 02H, ... 0FH.

[Problems to be Solved by the Invention] In the above-mentioned conventional terminal unit, when there is an unused analog input signal address assigned to one terminal unit, that is, when there is a terminal not used for the analog input terminal. The polling and the predetermined transmission for the address corresponding to the unused input terminal are configured.

Therefore, when using a multi-point input type terminal device, if there is an unused input terminal, the address corresponding to this input terminal cannot be used effectively and a terminal that can be connected within a certain amount of address setting range The number of devices is limited (up to 16 in the above example). Therefore, there is a problem that the terminal units and the analog input devices connected to the terminal units are limited in places where they can be dispersed, and the system configuration cannot be flexibly dealt with.

Further, generally, in A / D conversion, the amount of digital signal corresponding to one amount of analog signal is large. For example, in the case of A / D conversion with 8-bit resolution, one amount of analog signal is digital
Equivalent to 8 points of N "/" OFF "signal.

Therefore, even if there is an unused input terminal as described above,
Since serial transmission corresponding to the address of this input terminal is performed, there is a problem that the number of signal points in communication increases and a transmission delay occurs due to unnecessary data transmission.

The present invention has been made in view of the above-mentioned conventional problems, and the object thereof is the number of addresses used by the terminal device, that is, the analog input signal sent by the terminal device after the A / D conversion. By making it possible to set the number of points, unnecessary A / D conversion and its communication can be eliminated for each terminal device, and it is possible to realize a more efficient and shortened transmission time system. It is to provide a D conversion device.

[Means for Solving the Problems] Therefore, in the present invention, one center unit and a plurality of terminal units to which controlled devices are connected are connected by a common signal line, and the center unit is connected to the common signal. Cyclic polling with a different address for each of a plurality of terminal units via the line, the terminal unit specified by the address A / D conversion of the analog signal taken from the controlled device the common signal In an A / D conversion device built in the terminal unit in a system for serial transmission to a center unit via a line, a plurality of input terminals for capturing analog signals and an analog signal input to the plurality of input terminals are provided. Input switching means for sequentially capturing by switching, and an analog signal captured by switching of the input switching means is a digital signal. An A / D converter for converting into, and an input amount setting means for setting the number of input terminals capable of capturing an analog signal by switching the input switching means among the plurality of input terminals,
According to the number set by the input amount setting means, the A /
An address allocating means for allocating an address to the digital signal converted by the D converter is provided.

[Operation] According to the above configuration, the number of addresses is assigned to the A / D-converted digital signal according to the number set by the input amount setting means.

Embodiments Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a circuit block diagram of an A / D converter according to an embodiment of the present invention. The A / D conversion device shown in the figure is a main part of the terminal unit T in the system described above with reference to FIG. 4, and is taken in at each of the analog input terminals AI0 to AI15 as shown in FIG. The analog input signal is A / D converted by this A / D converter and is transmitted to the center unit C via a transmission circuit (not shown) in response to polling of the center unit C. As described above, one A / D conversion device of this example has 16 analog input terminals to which 16 controlled devices can be connected, so that 16 addresses of analog input signals can be assigned.

Hereinafter, each element shown in FIG. 1 will be described. In the figure, 300 to 315 are a pair of analog switches provided corresponding to each of the analog input terminals AI0 to AI15, and 2 is an amplifier circuit inserted between the pair of analog switches. The amplifier circuit 2 is connected to each of the analog switches 300 to 315 so as to be commonly inserted between the analog switches. These analog switches have a low impedance at a low level of a control signal, which will be described later, and close (turn on) the circuit.

R10-R115, C10-C115 are analog switches 300-
A resistor and a capacitor provided between 315 and a CPU to be described later, and by closing (turning on) the analog switch, a circuit for holding the captured analog input signal is configured.

4 is a Dig switch as an external operation switch for setting the number of analog input signal addresses occupied by the A / D converter, that is, the number of analog input terminals to be used,
It is possible to set 16 kinds of settings, which consist of 4 changeover switches. 1 is a CPU, and analog input terminals AI0 to AI
15 open ports corresponding to each of the input ports Ai0 to Ai15 and analog switches 300 to 315 for receiving analog input signals input from these terminals.
It has output ports Po0 to Po15 for outputting control signals for closing (off / on) and input ports Pi0 to Pi3 for inputting switch signals set by the Dig switch 4. In addition, CPU1 is an A / D converter 1 for A / D converting the analog input signals captured at input ports Ai0 to Ai15.
A, and a table 1B described later with reference to FIG.

FIG. 2 is a conceptual diagram showing details of the table 1B shown in FIG. 1, and 16 kinds of setting data “0” to the Dig switch 4
It stores the data of the analog input terminal used corresponding to each "F". For example, when the Dig switch 4 is set to "2", the CPU 1 refers to Table 1B and determines that the input terminals AI0, AI1, AI2 are the used input terminals and the number of analog input signals is three. , Based on this, the third
According to the address of each terminal unit set when configuring the system as shown in the figure, the address assignment of the analog input signal, that is, the address assignment of the converted digital signal is performed. For example, the address of the digital signal A / D converted by the terminal unit T1 in FIG. 3 is 00H to 03H.
Thus, when the address in the polling of the center unit corresponds to this address, the digital signal of this address is transmitted.

As explained above, it is possible to effectively use the address setting range of the analog input signal by setting the number of analog input terminals used in one A / D conversion circuit (terminal unit) with the Dig switch. Thus, it becomes possible to configure a system in which the number of terminal units is increased compared to the conventional one.

Such a system configuration is shown in FIG. As shown in the figure, in each of the terminal units T1, T2, T3, T4 ... Dig
By setting the switches to "3", "1", "7", "3" ..., the number of analog input signals taken in by each terminal unit is 4, 2, 8 ... Is set to.

Further, in each terminal unit, the same address setting as that of the Dig switch 4 is carried out for each terminal unit as shown in FIG. 3, whereby allocation of four analog input signals taken in by the terminal unit T1 is performed. The address can be 00H, 01H, 02H, 03H.

[Effects of the Invention] As is apparent from the above description, according to the present invention, the A / D-converted digital signal is allocated with this number of addresses according to the number set by the input amount setting means.

As a result, in a system in which a terminal unit equipped with the A / D conversion device of the present invention is arranged, unnecessary A / D conversion and communication therefor can be eliminated for each A / D conversion device. It is possible to realize an efficient system in which the transmission time is shortened.

[Brief description of drawings]

FIG. 1 is a circuit block diagram of an A / D conversion device according to an embodiment of the present invention, FIG. 2 is a conceptual diagram showing details of the table shown in FIG. 1, and FIG. 3 is A shown in FIG. A block diagram of a system having an A / D converter as a main part of a terminal unit, FIG. 4 is a block diagram of a system configured using a conventional A / D converter, and FIG. 5 is a block diagram of the system shown in FIG. It is an explanatory view for explaining data transmission and reception between a center unit and a terminal unit. 1 ... CPU, 1A ... A / D converter, 1B ... table, 2
…… Amplifier circuit, 4 …… Dig switch, 300 to 315 …… Analog switch, Ai0 to Ai15 …… Analog signal input port, Po0 to Po15 …… Control signal output port, Pi0 to Pi3 ……
Control signal input port, AI0 to AI15 ... Analog input terminal.

Claims (1)

[Scope of utility model registration request] 1. A center unit and a plurality of terminal units to which a controlled device is connected are connected by a common signal line, and the center unit is connected to each of the plurality of terminal units via the common signal line. It cyclically polls at different addresses, and the terminal unit specified by the address serially transmits the data obtained by A / D converting the analog signal taken in from the controlled device to the center unit via the common signal line. In the A / D converter incorporated in the terminal unit in the system, a plurality of input terminals for receiving analog signals, and an input switching means for sequentially capturing analog signals by switching the analog signals input to the plurality of input terminals are provided. An A / D converter for converting an analog signal captured by the switching of the input switching means into a digital signal; Of the input terminals, input amount setting means for setting the number of input terminals capable of taking in an analog signal by the switching of the input switching means, and the A / A according to the number set by the input amount setting means.
And an address assigning means for assigning an address to the digital signal converted by the D converter.
A / D converter.