JPH028927A - Analog input/output device - Google Patents

Abstract

PURPOSE:To obtain an analog input/output device constituted of one device having input- and output-side functions by causing a microprocessor MP to decide whether the function as an analog input device or that as an analog output device is to be given to the device based on a read value. CONSTITUTION:When power is applied, a microprocessor MP connects a switch SW to a contact (d) side and turns on the channel CH21 of an output multiplexer MX2. Then a D/A converter outputs a 1V voltage. Thereafter, the microprocessor MP connects the switch SW to another contact (a) side and reads the signal of the channel CH1n of an input multiplexer MX1 by turning on the channel CH1n. The read signal is A/D-converted through a comparator CMP, a register RG, the microprocessor MP, and the D/A converter. After the A/D conversion, whether the magnitude of the A/D-converted signal is equal to the magnitude, namely, 1V of the signal outputted from the D/A converter. Then programs for operations are prepared so that this device can operate as an analog output device when the magnitude of the A/D converted signal is 1V and an analog input device when the magnitude is a voltage of about 0V.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an analog input/output device for processing various analog signals obtained from a field by a computer and outputting the same to the field as an analog signal. relates to an analog input/output device that allows sensors and actuators to be connected to a computer that handles digital signals.

(Prior Art) FIG. 4 is a block diagram showing an example of a system using a conventional analog input/output device.
is a computer that handles digital signals, ANI is an analog input device that converts analog signals from the field into standardized signals that can be handled by computer CP, and ANO is an analog output that outputs signals from computer CP to the field. It is a device.

In the analog input device ANI, MXI is an input multiplexer that sequentially selects a large number of input analog signals Vn1 to Vnn and applies them to the buffer amplifier BA, and AD is an A/
The D converter, IFI, connects the output of the A/D converter AD to the bus BS.
This is an interface that outputs to the control machine CP side via.

In the analog output device ANO, IF5 is the total! ! An interface that receives data from the L machine CP, DA is a D/A converter that converts digital signals to analog signals,
MX2 is an output multiplexer that sequentially supplies an analog signal from the D/A converter DA to each sample and hold circuit SHI to SHn.

(Problem to be solved by the invention) Conventional systems configured in this way have separate functions on the input side and output side, so as an analog signal input/output device, one for the input side and one for the output side are used. It was necessary to prepare two devices, one for the side and one for the side. For this reason, there were problems in that the number of devices increased and the configuration became complicated.

The present invention has been made in consideration of these problems, and its purpose is to provide an analog input/output system that can have input and output functions using a single device with a simple configuration. The goal is to provide equipment.

(Means for Solving the Problem) FIG. 1 is a block diagram showing the basic configuration of the present invention. In FIG.
DA is an input multiplexer that selects and inputs AVn; AD is an A/D conversion means that converts the analog signal selected by this input multiplexer MX1 into a digital signal; DA;
is a D/A converter that converts a digital signal into an analog signal, MX2 is an output multiplexer that selects and outputs the analog signal from the D/A converter DA to a large number of analog signal holding means SHI to SHn, and FB is an output Input signal from multiplexer MX2 to multiplexer MXI
Feedback means MP is a microprocessor that controls the input multiplexer MX1, the A/D conversion means AD, the D/A conversion means DA, and the output multiplexer MX2.

Note that MU is a memory that stores a database, and C
P is a higher-level computer connected via a higher-level bus BS.

(Function) When the power is turned on, the microprocessor MP outputs a predetermined signal from the D/A conversion means DA to the output multiplexer MX2, reads a signal from the feedback means FB via the input multiplexer MXI, and converts the read signal to the output multiplexer MX2. The value determines whether the device functions as an analog input device or an analog output device.

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

FIG. 2 is a block diagram showing an embodiment of the present invention. In FIG. 6, the same parts as those in FIG. 1 are not denoted by the same reference numerals. The A/D conversion means AD includes a comparator CM having one input as the signal from the input multiplexer MXI.
P, a register RG in which data is stored in accordance with the signal from this comparator, a microprocessor MP, and a D/A
The signals from the converter DA and the D/A converter are transferred to the comparator CMP.
The microprocessor MP is connected to the upper gage meter CP via the upper interface IP.

Here, when the device is used as an analog input device, the signal holding means SHI to SHn as illustrated are not required on the output side of the output multiplexer M X 2 and are not implemented in the device.

The operation of the apparatus configured in this way will be explained next.

FIG. 3 is a flowchart showing an example of the operation performed when the microprocessor MP is powered on.

When the device is powered on, the microprocessor MP first connects the switch SW to the contact d side, and
In output multiplexer MX2, channel CH2
1 is connected, and a predetermined voltage, for example, a voltage of 1 is output from the D/A conversion means DA (step 1.2).

Next, connect the switch SW to the contact a side, and connect the channel CH1n of the input multiplexer MXI,
Read the signal of this channel CH1n (step 3
．． 4) In this state, comparator CMP, register RG,
A circuit consisting of a microprocessor MP and a D/A conversion means DA forms an A/D conversion loop via a switch SW, and converts a signal applied to one end of the comparator CMP into a digital signal.

Next, it is determined whether the magnitude of the A/D converted signal is the predetermined voltage output in step 2 (step 5).

Here, assuming that signal holding circuits SHI to SHn are connected to the output side of the output multiplexer MX2, the signals held here are applied to the input side of the input multiplexer MXI via the feedback means FB. . On the other hand, if the signal holding circuits SH1 to SHn are not connected to the output side of the output multiplexer MX2, the signal applied to the input side of the input multiplexer MXI via the feedback means FB will be near ov.

In step 5, if the magnitude of the read signal is a predetermined voltage, for example IV, an operating program is set to operate as an analog input device (
Step 6).

On the other hand, if the voltage is not the predetermined voltage in step 5, for example, if the voltage is around 0.times., an operating program is set to operate as an analog input device (step 7).

The microprocessor MP first performs such an operation when the power is turned on, thereby determining whether the signal holding means is connected, and depending on the result, whether the microprocessor MP thereafter operates as an analog input device or an analog output device. I am deciding what to do.

In step 6, which operates as an analog output device, the switch SW is connected to the contact d side, and reads, for example, the database sent from the higher-order meter CP to the memory MU and held there at a predetermined cycle. , this is D/A
The converted signal is outputted to the signal holding means SH1 to SHn for each point via the output multiplexer MX2.

In step 7, which operates as an analog input device, the switch SW is connected to the contact a side, and the input multiplexer M
The input signals AVI to AVn at each point are sequentially input to D via
/A conversion and stored in the memory MU as a standardized database.

The database stored here is read out by the host computer CP as needed.

In the above embodiment, the A/D conversion means is the comparator CM.
The circuit is configured with a loop consisting of P, register RG, microprocessor MP, D/A converter DA, and switch SW, but switch SW may be omitted, and register RG is connected to microprocessor MP. You may use what is inside. Furthermore, an A/D converter may be provided on the input side of the microprocessor.

(Effects of the Invention) As described in detail above, according to the present invention, the main configurations of the analog input device and the analog output device can be shared, and the input side and output It is possible to realize an analog input/output device that has functions with the side, and it is possible to reduce costs.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the basic configuration of the present invention, Figure 2 is a block diagram showing the basic configuration of the present invention.
3 is a flowchart showing an example of the operation performed by a microprocessor, and FIG. 4 is a block diagram of the structure of a conventional device. MXI...Input multiplexer MX2...Output multiplexer AD...A/D conversion means MP...Microprocessor DA...Archive)/A converter FB...Feedback means Diagram 2/ icare alexa

Claims (1)

[Claims] An input multiplexer that selects and inputs a large number of analog signals; A/D conversion means that converts the analog signal selected by the input multiplexer into a digital signal; and converts the digital signal into an analog signal. D/A conversion means; an output multiplexer that selects and outputs analog signals from the D/A conversion means to a large number of analog signal holding means; the input multiplexer, the A/D conversion means, the D/A conversion means; A microprocessor for controlling an output multiplexer; and feedback means for applying a signal from the output multiplexer to an input side of the input multiplexer, the microprocessor outputting a predetermined signal from the D/A conversion means when the power is turned on. outputting the signal to a multiplexer and reading a signal from the feedback means via the input multiplexer, and determining whether the device is to function as an analog input device or an analog output device depending on the value of the read signal; An analog input/output device featuring: