DE3013847A1 - Analogue channel switching unit - uses selectors addressed by computer to couple with single A=D converter - Google Patents

Abstract

An analogue switching system allows a large number of channels to be addressed and the signals processed by an A/D converter to provide an input to a computer. The system has several analogue channel switching stages (3,4), each receiving signals from a number of channels (9,10). The computer (1) has an address bus (7) that communicates with the analogue to digital converter (2), the channel selectors (3,4) and output stages (5,6). One group of address bits identifies the channel selector and another group identifies the specific channel. A control line (8) controls activation of the unit addressed. The channel selection may be expanded upto the limit of the addressing capability.

Description

Designation: analog interface

The analog interface is the link between the computer and the analog environment.

Measured values from the environment are converted into electrical currents by sensors Voltages or resistance values implemented. These are controlled via the analog interface through the computer, entered into the computer.

On the other hand, the computer is mediated by the analog interface able to influence the environment through relay and control outputs.

The input of analog values is made possible by the analog channel circuit and the analog-to-digital conversion achieved.

The analogue values present in parallel are transmitted through the analogue channel circuit in one controlled by the computer program Order and Frequency in series, i.e. one after the other, to the input of the analog-digital converter placed.

The analog-to-digital converter converts the analog values into digital values that the computer can accommodate.

Such known devices are not very flexible and very expensive. They are intended for a fixed number of analog channels. A change in number is difficult to do.

The analog-to-digital conversion is done with a fixed resolution of the analog value. There is no possibility of adapting to the specific Mission. An output of control signals is generally not provided.

The invention is based on the object of eliminating these disadvantages. This is done according to the invention in that the analog interface is made up of individual Devices, which are selected depending on the application and by one of the Devices fulfills the function of analog-digital conversion, another device fulfills the function Analog channel switching, a third device has the function of outputting control signals and that the devices channel switching and output of control signals can be cascaded (parallel connection of other devices of the same type).

The analog channel switch device and the output device have only one limited number of channels. Due to the cascading capability, the number of Analog inputs and outputs multiply and conveniently for practical use adapt.

In a further embodiment of the invention are between the computer and the analog interface, on the one hand, lines are provided for the transmission of data and addresses and on the other hand a control line, since the program is on 2 different States, which are designated with 0 and 1, can be set.

The analog-digital converter is activated by the one switching state of the control line initialized. At the same time, the other devices are made inactive. Through the In other switching states, the analog channel switches and the output devices are initialized and the analog-to-digital converter made inactive.

The computer is either in the one switching state of the control line can record an analog value or in the other switching state of the control line send information to the analog interface.

This information can be the selection of one of the connected analog channel switches and choice of a channel in this device or choice of an output device and choice of one certain output line of this output device and whether this output line is set or is reset.

Each device, analog channel switch and output device, has a device address, which is set in the device. Any used within the closed system The device therefore has a different address that the computer uses to set the corresponding Device. The device address is therefore expediently through switches adjustable.

Figure 1 shows how the computer with the analog interface via the Data address lines and the control line are connected to one another.

1 is the computer 2 the analog-to-digital converters 3 + 4 are analog channel switches 5 + 6 are output devices 7 is a cable bundle that consists of a number of lines, transmit the data and addresses. All devices in the system are through the data address lines 7 connected to each other.

8 is the control line, which also connects all devices with one another.

Lines 9 + 10 of the analog channel switches 3 + 4 are the analog input channels, through which the various analog values are entered.

Line 13 is the analog bus line through which the analog values are fed serially to the analog-to-digital converter 2.

11 + 12 are the output lines of the output devices 5, 6 image 2 shows the data address lines 14-21 and the control line 8.

These lines connect all devices with one another.

The function is as follows.

The computer 1 controls the system. When he takes a reading of a channel 9, 10 would like to query the analog switch 3, 4, it becomes the control line first Set 8 to logical 0.

Then it will send out the device address and the desired channel Select.

The binary state 0 or 1 of the lines 14, 15, 16, 17 gives the Device address. 16 devices can be addressed with these 4 lines.

The binary state of the lines 18, 19, 20, 21 gives the desired Channel on. This will select 1 channel out of 16 channels. This measure will the associated analog value via the analog bus line 13 to the input of the analog-digital converter 2 laid.

Then the computer will set the control line to logic 1. Through this the analog-to-digital converter 2 is initialized while the other devices are inactive will. At the same time, the analog-to-digital converter converts and provides the digital value onto data address lines 14-21.

In a next step, the computer will take over the digital value.

This mode of operation applies to analog-to-digital converters and their output signal 8 bits wide or smaller.

If it is assumed that it is a higher resolution Analog-to-digital converter acts, e.g. 12 bit, then the 8 data address lines are not sufficient. In this In this case, the 12-bit signal is divided into 2 portions of 6 bits each and one behind the other transferred to computer 1.

There are 2 lines for the transmission of the 6-bit wide digital value free that computer 1 uses by sending 2 different bit patterns, to request the upper 6 bits and the lower 6 bits from the analog-to-digital converter 2.

The following procedure is used to send a signal via the control line necessary.

The control line is set to logic 0. This will become the output devices prepared to receive an address. Then the address is again via 4 data address lines of the data address trunk group 7 is sent. At the same time, the desired channel and the information as to whether this channel is set or reset about the others Data address lines of the data address line bundle 7 sent.

Claims (1)

Claims claim @ Method and device for inputting Analog values in the computer and output of control signals characterized by that the device consists of individual devices (modules), depending on the application can be selected and that one of the devices (modules) supports the analog-digital conversion function is fulfilled, another device has the function of analogue channel switching and a third device the function output of control signals and that the number of analog channels and Control outputs through parallel connection of further devices (modules) Analog channel switches and output devices can be multiplied. Claim 2: Method and device according to Claim 1 thereby characterized in that a control line is provided in addition to the data address lines which is controlled by the computer, can take 2 states and that in that one state of the analog-to-digital converter is addressed and that during the other State the devices analog channel switches and output devices are addressed and the devices are prepared for the transmission of a device address and channel selection are. Claim 3: Device according to Claim 1 + 2, characterized in that that every device, analog channel switch and output of control signals, a device address which is to be set internally and that via part of the data address lines a bit pattern is sent to select the device. and that over another part of the lines a bit pattern for Selection of the channel is sent. Claim 4: Method according to Claims 1 - 3, characterized in that that when the information is transmitted to the output device, one of the data address lines is used to convey that the selected output channel is either set (Signal on) or reset. Claim 5: Method and device according to Claims 1-3 thereby characterized in that an analog bus line (13) is provided which carries the analog values one after the other in a sequence and time sequence determined by the computer from the analog channel switches (3, 4) to the analog-digital converters (2). Claim 6: Method and device according to Claim 1, 2, 3, 5 thereby characterized in that in the case of analog-to-digital converters with a digital output signal, which requires more lines than for the parallel transmission of the digital signal Data address lines (7) are present that the digital signal in 2 or more portions split serially and that data address lines which the computer uses to convey what part of the digital signal to be transferred to the computer.