DD284336A5 - CONNECTION SYSTEM FOR FIELD UNITS TO A CONTROLLER - Google Patents

Abstract

The invention relates to a connection system for field units to a control computer. It refers to the connection of field units to a control computer generally in process control systems. The field of application is the connection of such field units, which have both analog and digital, preferably serial Anschluszsignale. For the connection of these field units only a simple transmission line is used, over which both digital serial and analogue signals are transmitted. Switches are provided on the side of the control computer and on the side of such field units which have analog connection signals, which connect field unit side analog channel units for transmitting or receiving analog signals corresponding converter units arranged on the control computer side for analog / digital or digital / analog signal conversion. The control of the changeover switch is derived on the control computer side by a signal type recognition and the selection of the field unit and its operating mode is effected by digital serial transmission. FIG {Prozeszsteuersystem; Control computer; Field unit; transmission line; digital serial signal; analog signal; Switch; Conversion unit; Analog channel unit; Signal type detection; mode}

Description

For this 1 page drawings

Field of application of the invention

The invention relates to the connection of field units to a control computer in control systems for processing and processing, generally in process control systems. Such generally on site and therefore remote, arranged field units fulfill a variety of measuring and control functions and have a variety of interfaces. The application of the invention is particularly possible if these field units in addition to analog and digital, preferably serial connection signals, the signal conversion in or out of the digital domain of the control computer at a central location by simply existing conversion units and the Vorbindung the field units with the control computer via a simple transmission line should be made.

Characteristic of the known state of the art

From DE-OS 3121SS8 a method and a device for converting digital signals into analog output variables which are assigned to a plurality of output channels are known, in the case of the digital signals present in a central processing unit in a central D / A converter in chronological succession into analogue The analog signals were taken over by channel-related sample-and-hold circuits as soon as the central processing unit sent out the address of the associated output channel via an address bus. For this purpose, the analog bus and the address bus are routed to each output channel, each of which contains an address decoder. The disadvantage of this is that in addition to the analog bus, a separate address bus is routed to each output channel and from each output channel, the analog signal must be routed via a separate connection line to the unit to be acted upon. This requires a high amount of wiring on the output assembly and a high amount of cabling and connector expense for the connections to the connected units. Furthermore, the separate address bus does not allow general digital information to be transmitted to serving units.

In DE-PS 3317567 a computer-controlled time-division multiplex system for data transmission between a central control unit and a set of data stations which are connected via a signal line to the central control unit, disclosed in the address, control, acknowledgment and interruption data be transmitted. The data are recognized in their sequence and processed or stored accordingly.

The transmission of this data is provided in a signal form, wherein a digital / analog or analog / digital conversion of control data would be possible in the data stations. For this purpose, corresponding conversion devices would have to be provided in each relevant data station, which as cost-intensive elements would result in a high total expenditure.

From DE-OS 3304636 a device for the transmission and registration of data is further known, the unit on the data acquisition side with RF transmitter and RF coupling for supplying the data in a line system, preferably coaxial cable system, wherein the RF transmitter analog or digital values are modulated over the acquired data. The data transmitted via the line system are received by a central processing unit and assigned to predetermined counters for detection. The assignment is made for analog values by frequency selection and for digital values by appropriate addressing.

A disadvantage of this solution is considered that it requires a considerable carrier frequency engineering and modulation and demodulation, in particular for the frequency-selective distinction of the analog values in terms of their origin. In addition, it is only intended for one-directional operation of the consumption measuring devices to the central unit and the cost would increase significantly again for two-aided operation using their own resources.

Object of the invention

The aim of the invention is a reduction of the effort when connecting field units with analog and digital Anschluß3ignalen to a control computer.

Explanation of the essence of the invention

The main reason for the shortcomings set forth in the prior art is that, for the transmission of analogue and digital signals, either separate transmission lines are required, which transmit only analogue or digital signals in a dedicated manner, or when using a simple power system consuming carrier frequency modulation or demodulation, in particular for channel selection, are required.

Accordingly, the invention has for its object to provide a connection system for Feidäinheiten to a control computer according to the preamble, which only requires a simple transmission line for the transmission of analog and digital signals and to carry out the transmission of analog signals largely uses the existing means for digital serial transmission ,

According to the invention the object is achieved in that control computer side of the serial port of the first digital serial input / output unit and leading to the field units connection of at least one Wandloreinheit for digital / analog or analog / digital signal conversion to the multiple connection of a first switch, feldeinheitenseitig the serial port a respective second digital serial input / output unit and leading to the control computer terminal of at least one analog channel unit for receiving or transmitting analog signals, 1ie can cooperate with the at least one control computer side converter unit are routed to the multiple connection of a respective second switch and the single terminals of the first switch , each second switch and the serial ports of all other digital serial input / output units are connected to each other via the simple transmission line, wherein the control input de s first switch is connected to a first output of a first transmission controller whose mode-determining input connected to the output of a signal type memory connected via a register i3t, and the control input of the respective second switch is connected to a first output of a respective second transmission control whose mode-determining input with the parallel data connection of each second digital serial input / output unit is in communication.

It is expedient that sense control terminals of the converter units are connected to further outputs of the harvested transmission control.

It is further appropriate, dal? on the analog channel units existing channel control terminals for selecting the analog channel to be transmitted directly and sense control terminals via a gate with outputs of a Kanaladreßdekoders

connected to the input side of a Kanaladreßregister, wherein a further input of the gate member is connected to a second output of the respective second transmission control.

Furthermore, it is advantageous that the mode-determining input of the respective second transmission control is connected to the output of a mode decoder whose first input is connected to the output of a field unit address decoder, which is input to a field unit address register, and whose second input is connected to a mode data register.

embodiment

The invention will be explained in more detail with reference to the following embodiment in conjunction with the figure, which shows a block diagram of the connection system according to the invention.

In this embodiment, to a control computer 1, a plurality of field units 43,44,46,51 and 52, which are to be designed in different ways for the acceptance and delivery of analog and / or digital signals, connected via a simple transmission line 22.

The field connection unit 2 of the control computer 1, not shown, has a control unit, of which only the elements 3 to 11 of interest here are shown. These are a digital serial input / output unit 3 connected to its internal data bus 7, a signal type memory 4 driven by the internal address bus 8, whose data output is routed to the data bus 7 and to the input of the register 5, and a transmission controller 6 whose mode-determining input connected to the output of the register 5. The digital serial Eirv / output unit 3 is connected via an interrupt signal line 9 and the transmission controller 6 via a start signal line 10 and an end signal line 11 with a processing unit, not shown, to which the data bus 7 and the address bus 8 are guided.

The data bus 7 is further connected to the digital side of the converter units 13 and 18. The analog / digital conversion converter unit 13 includes, in series and in the direction of action, an analog value memory 16, an A / D converter 15 and an input buffer 14, and the digital / analog conversion converter unit 18, an output buffer 19, a D / A converter 20, and a Driver Amplifier 21. A sense control terminal 17 of the analog value memory 16 is connected to a second output of the transmission controller 6.

The serial port of the digital serial input / output unit 3 and the analogue terminals of the converter units 13 and 18 are fed in sequence to the multiple terminal 1 ... 3 of a changeover switch 12, its single connection to the transmission line 22 and its control terminal to a first output of the transmission control 6 is connected. The switch 12 connects either the serial port of the digital serial input / output unit 3, the analog input of the converter unit 13 or the analog output of the converter unit 18 to the transmission line 22, depending on the value of its control signal.

On the side of the field units, the further explanation is given for the field unit 43, which has only analog input and output signals 40.1 and 40.2 or 35.1 and 35.2. This is connected upstream for connection to the transmission line 22 of the connection adapter 23, in which the transmission line 22 is guided to the single terminal of the switch 31. At the terminal 1 of its multi-port, the serial port of a digital serial input / output unit 24 is connected, which is part of a control circuit of the elements 24 ... 30.

The parallel data terminal of the digital serial input / output unit 24 is connected to a register field 25. A ready code register 25.1 and an end code register 25.2 provide their contents to the digital serial I / O unit 24, to which their activation inputs are connected to outputs of a transfer controller 29, which are also routed directly to the digital serial I / O unit 24. Further, a mode data register 25.3 is directly passed and a field unit address register 25.4 via a field unit address decoder 26 to a mode decoder 28 whose output is connected to the mode-determining input of the transfer controller 29.

A first output of the transmission controller 29 is applied to the control input of the switch 31. At the terminal 2 of the switch 31, the output of the analog channel unit 32 is connected to send analog signals, which connected in series a transmission switch 34, the multiple input to the analog outputs 35.1 and 35.2 of the field unit 43rd is connected, and a drive amplifier 33 includes.

At the terminal 3 of the switch 31, the input of the analog channel unit 37 is connected to receive analog signals, connected in series a Empfangsumschalter 38 and each connected to an output of its multiple output channel analog value memory 39.1 and 39.2 contains their outputs to the analog inputs 40.1 and 40.2 of the field unit 43rd are connected.

Channel control ports 36 and 41 of the analog channel units 32 and 37 are direct and scan control ports 42.1 and 42.2 of the analog channel unit 37 are connected for timing control via a gate 30 to outputs of a channel address decoder 27 whose input is biased by a channel address register 25.5. The time control input of the door member 30 is occupied by a second output of the transmission controller 29.

To the transmission line 22 are further connected a field unit 44 containing a connection adapter 45 as an integrated component, a field unit 46, in which the digital serial Eirv / output unit 48 of the integrated connection adapter 47 is connected to a control and a status register 49 and 50, respectively an exclusively digital serial port array unit 51 in which the digital serial I / O device is directly connected to the transmission line 22, and an exclusively digital serial port array unit 52 in which the digital serial I / O device 56 is connected to the transmission line via a port adapter 53 22 is connected. The operation of the connection system is as follows:

The case of the analog output, for example for a control signal output to a motor, will first be described in detail.

For this purpose, the field connection unit 2 receives from the control computer 1 the instruction to output a control signal by transferring the field unit address, the channel address, the digital value of the control signal and certain control parameters, ι. As regards the timing of the issue. The unillustrated processing unit of the field connection unit 2 stores this instruction

in its working memory, which is not shown, and initiates after evaluation of the control parameters, in particular the predetermined time for the output, the execution.

Via its address bus 8, it supplies the field unit and the channel address to the signal type memory 4 which, in the form of a list, assigns information about its signal type to each field unit and channel address, that is, whether it is an analog or digital input or output signal , In the present case, the signal type memory 4 outputs the information for an analog output signal, which returns via the data bus 7 first to the processing unit, which then the field unit · and channel address together with mode data, which includes a flag on the signal type, to the digital serial On - / output unit 3 transfers.

This sends out this data as an address and mode message in digital serial form via the switch 12 and the transmission line 22. The address and mode message is received by all field devices or upstream or integrated port adapters. In the connection adapter 23, the address and mode message via the switch 31 to the digital serial input / output unit 24. The switches 12 and 31 are preferably always in position 1 (home position) for connecting the serial input / output units 3 and 24th with the transmission line 22. Time-parallel to the transmission of the address and operating mode message, the processing unit loads the digital value of the analog signal to be output via the data bus 7 into the output buffer 19 of the converter unit 18. Thus, the digital value is available at the inputs of the D / A converter 20 then performs the D / A conversion. The converted analog signal passes through the Treibei amplifier 21 to the terminal 3 of the switch 12, where it is provided for transmission. Meanwhile, the address and mode message received from the serial I / O unit 24 is transferred from this after a serial / parallel conversion to the register field 25, the mode information in the mode data register 25.3 and the address information in the field unit address register 25.4 and in the Channel address register 25.5. The output of the field unit address register is passed to a field unit address decoder 26, which only becomes active if the received field unit address corresponds to its own address, which should be the case here. The output of the field unit address decoder 26 is fed to the mode decoder 28, which is applied to another input from the mode data register 25.3, and activates its output if the field unit address is true and mode data for an analog signal type is present.

As a result, the transmission control 29 is started via its mode-determining input, which first activates the standby code register 25.1 and causes the serial input control to send back a ready code to the field connection unit 2 of the control computer 1. There, the readiness message is received by the serial input / output unit 3 and read out by the processing unit after it has been signaled the reception via the interrupt signal line 9. After evaluation, the processing unit activates the transmission control 6 via the start signal line 10, which performs its control functions in accordance with its own timer. In the terminal adapter 23, the transmission controller 29 switches the switch 31 to position 3 due to the decoded mode "analog output" and in accordance with its timer to connect the transmission line 22 to the analog channel unit 37.

In port adapters that do not match the address information contained in the address and mode message with their own address, the respective mode decoder decodes the mode "analog transmission with foreign field unit", whereupon this only their second switch to a rest position 0 for the duration of the analog transmission bring to separate the serial input of their respective serial input / output unit of the transmission line 22 and thus to keep unauthorized signal levels due to the analog signals to be transmitted from him.

Only digital serial port arrays that do not require a port adapter can, for the same purpose, place the serial input of their digital serial input / output device in a high-impedance state. After movement of the switch 31 of the connection adapter 23 in position 3, the transmission controller 6 switches in the field connection unit 2 of the control computer 1 in accordance ihi as internal timer the switch 12 in the position 3 and thus the analog connection available at the associated terminal on the transmission line 22. The analog signal continues to the terminal adapter 23 and in this via the switch 31 to the input of Analogkannleinhoit 37 and the input of their switch 38th

This was previously a control signal from an output of Kanaladreßdekoders 27 fed, whereupon he assumed the position 1 as shown. The analog signal is therefore supplied to the Kanalanalogwertspeicher 39.1, which it is stored by activating its Abtaststeueranschlusses 42.1 by the gate member 30. For this purpose, the gate member 30 is supplied from the transmission controller 29 a time-determining pulse for the sampling. From the output of Kanalanalogwertspeichers 39.1 the analog signal reaches the analog input 40.1 of the field unit 43 and is there ready for processing.

After this process, in the field connection unit 2 by the transmission control 6 of the switch 12 and in the terminal unit 23 -as well as in all other Anschlussadaptern - brought by the transfer controller 29 of the switch 31 in accordance with internal timer in its home position 1, whereby the digital serial Eirv / Output units 3 and 24 are again connected to each other via the transmission line 22 and ready for the digital serial transmission. The transmission controller 6 signals this state of the processing unit via an end signal line 11 and the transmission controller 29 is activated as a last resort, the serial input / output unit 24 and the Endekodeereister 25.2 for transmitting its contents to the field connection unit 2. The serial Eirv / output unit 3 signals the reception of the end code of the processing unit via the interrupt signal line 9, whereupon the processing unit reads out the end code and, by evaluation, checks the proper completion of the analog transmission, thus completing it.

At the Ai.alogeingabe, z. For example, to query an analog Druckmeßwertes, takes place with respect to the initiation and termination by means of the digital serial transmission basically the same process as in the analog output, but now the signal type memory provides the signal type information for the mode "analog input." The actual transmission of the analog signal to the analog input requires the following other measures: The changeover switches 12 and 31 are brought to position 2, whereby the analogue-to-digital conversion unit 13 in the field connection unit 2 is provided with the analog channel unit 32 for transmitting analog signals in the terminal adapter 23. The channel address decoder 27

controls after feeding dor valid channel address the transmission channel switch 34 in the corresponding position, after

Representation in the position 1, whereby the analog signal from the analog output 35.1 of the field unit 43, via the Driver amplifier 33 and the switch 31 is sent to the transmission line 22. From this, the analog signal passes through the switch 12 to the input of the converter unit 13 and the Analog value memory 16, which is on a timely actuation of its Abtaststeueranschlussss 17 by the Transmission control β down, with which the Analogübertragurrg is completed. By appropriate activations by means of

the internal timer of the transmission controllers 6 and 29, the production of the ground state to the digital serial

Transmission initiated. Regardless of the analog signal passes on the A / D converter 15, the digitally converted "analog value in a Provides input buffer 14 for reading by the processing unit. For exclusively digital serial input, only the digital serial input / output units are used. In

In this case, in the field connection unit 2, the signal type information supplied from the signal type memory 4 signals

Transmission control 6, the mode "digital input / output", whereupon this leaves the switch 12 in the position 1 and

the converter units 13 and 18 are not activated. On the field unit side, the address and mode message causes

Connection adapter 23 also the detection of the operating mode "digital input / output", whereupon the transmission controller 29

leaves the switch 31 in the basic position 1 and the analog channel units 32 and 37 are not actuated. Thus, all digital serial I / O units remain connected through the transmission line and can be known between them

Way a digital serial data exchange take place. Within the framework of the proposed solution, the following variants of the coupling of field units can be realized:

- From the field unit 43 only analog signals are accepted or delivered. It is therefore preceded by a connection adapter 23, which can be implemented as a highly integrated circuit, for example as a user-specific integrated circuit (ASIC), on a small adapter assembly which is arranged between the connector of the transmission line 22 and the connector of the field unit 43.

- The field unit 44 also processes only analog signals, but the terminal adapter 45 is structurally integrated into it, so that it can be connected directly to the transmission line 22.

- In the field unit 46, in which the terminal adapter 47 is also integrated, the serial EinVAusgabeeinheit 48 is additionally connected to control and status registers 49 and 50 in order to exchange some digital information with the field unit 46 can.

The field unit 51 sends or receives only digital serial data via its serial input device, which is functionally designed to switch off for the time of the analog transmission from the transmission line 22.

The field unit 52 represents a non-system digital serial-line device in which the serial input / output unit 56 can not be turned off from the transmission line 22 during the analog transmission. It is therefore a connection adapter 53 upstream, which contains the control circuit and the switch 31 of the connection adapter 23 substantially. By connecting the serial port of the device's digital serial input / output unit 56 to the serial port of the digital serial output device 55, which is further connected to the port 1 of the switch 54, separation takes place from the transmission line 22 for the duration of the analog transmission.

Claims (4)

1. connection system for field units to a control computer, the control computer side a first digital serial input / output unit and converter units for digital / analog and / or analog / digital signal conversion, the digital side via a bus connected to the control computer, and field unit side further digital serial I / O units and analog channel units for receiving and / or transmitting analog signals associated with the processing units of the field units, and registers for storing received and to be transmitted address and control data and address decoder for detecting the field unit and channel address contains, and at the field units are connected via a simple transmission line to the control computer, characterized in that the control computer side of the serial port of the first digital serial input / output unit (3) and leading to the field units connection at least one of the converter unit to the multiple connection of a first changeover switch (12), the unit unit side of the serial connection of a respective second digital serial input / output unit (24) and the connection to the control computer at least one of the analogue channel units (32. 37), which can cooperate with the at least one control computer-side converter unit (13; 18) are led to the multiple connection of a respective second switch (31) and the single terminals of the first switch (12), each of each second switch (31) and the serial Connections of all other digital serial input / output units via the simple transmission line (22) are interconnected, wherein the control input of the first switch (12) to a first output of a first transmission controller (6) is connected, whose mode-determining input to the output of a signal type memory (4) is connected via a register (5), and the control input of the respective second changeover switch (31) is connected to a first output of a respective second transmission control (29) whose mode-determining input is connected to the parallel data connection of the respective second digital serial input. / Output unit (24) communicates. 2. Connection system according to claim 1, characterized in that Abtaststeueranschlüsse (17) of the converter units (13; 18) are connected to further outputs of the first transmission control (6). 3. Connection system according to claim 1, characterized in that at the analog channel units (32; 37) existing channel control terminals (36; 41) for selecting the analog channel to be transmitted directly and Abtaststeueranschlüsse (42.1; 42.2) via a gate member (30) with outputs of a channel address decoder (27) are connected, the input side to a Kanaladreßregister (25.5) is connected, wherein the gate member (30) on the input side is further connected to a second output of the respective second transmission control (29). 4. connection system nac'i claim 1, characterized in that the mode-determining input of each second transmission controller (29) to the output of a mode decoder (28) is connected, the first input to the output of a Feldeinheitadreßdekoders (26), the input side to a Field unit address register (25.4) is guided, and whose second input to an operating mode data register (25.3) is connected.