DD139676A3 - CIRCUIT ARRANGEMENT FOR A PROGRAMMABLE CONTROL DEVICE WITH PROCESS PITCHING - Google Patents

Description

Title of invention

Circuit arrangement for a programmable control device with process coupling

Field of application of the invention

The invention relates to a circuit arrangement for a programmable control device with process coupling, wherein the programmable control device has a computing unit and a program memory each having an image memory part for input / output. Contains output data and is connected via an interface and an address bus and an input / output data bus to an input / output unit for process coupling j with the interposition of galvanic decoupling * The circuit arrangement according to the invention is particularly applicable for machine tool controls.

Characteristic of the known technical solutions

! Turnerically controlled machine tools are increasingly being controlled by computers integrated in the control system. "The usual punctuation separation between central processing unit and peripheral input and output modules is used in process computer engineering.

This is especially necessary in order to keep the interference from the central unit.

Machine tools are subject to strong external electrical interference that requires a physical separation of the machine tool cabinet (power switch cabinet) of the control part contained the computer control. The computer control with its susceptible components, such as the read-write memory, the arithmetic unit and the data and Adreßbusleitungen for coupling the modules -with each other is particularly against external interference.

An essential factor for disturbances are the input and output lines that lead from the computer control to the machine tool control cabinet. In order to keep away the interference introduced by the power switch cabinet via these line connections, all inputs and outputs of the computer control are galvanically isolated from the rest of the system, ie. H'. Galvanic decoupling elements are connected in each of the connecting lines between the power circuit board and the computer control section. These may be electromechanical relays or also the optocouplers recently developed as semiconductor devices.

Known CUC controllers require a relatively high outlay for the galvanic isolation of the connection lines leading from the computer control part to the power switching cabinet, since a galvanic decoupling element is required per input / output signal line.

On average, about two hundred signal lines are required in a machine tool to be controlled, so that in addition to this number of ~ decoupling3elementen that bring high costs, also for the electrical Ansteue- = tion, an additional energy and space requirements arises. There are already known CKC controllers, which circumvent these disadvantages _s that between computer control part and power switchgear only a connecting cable with a relatively small number of lines is providedj whereby the problem of galvanic decoupling is reduced to a minimum of effort.

The signal exchange via the connection cable with few lines takes place in the manner of a "multiplexer" by an additionally provided signal transmission and reception unit. The advantage of the simplified transmission path with higher security against interference has thus been achieved only by additional circuit complexity-the multiplex operation-for the transmission of the pending different signals on the same lines.

The interference-free signal exchange between computer control part and Starlrstromschaltschrank as! Problem of process coupling to a programmable controller is treated in the known CNC controllers as a separate problem of signal transmission and as such separately solved technically. This is also clear from the fact that the data processing and adaptation is a circuit complex in the programmable controller by the data processed in the computer control part data are transmitted via address and Datenbusleitungen to the input / output unit. The adaptation of the bus structure of the computer control part to the bus structure of the Prözeßseite done by an interface circuit.

The input / output unit serves as a coupling part for the outer transmission lines.

All of these data processing and adaptation measures up to the input / output unit are assigned to a circuit complex d, h. Part of the fault-protected programmable control unit. The well-known CNC controls work for the input and output according to the interrupt principle, d. H. the internal circuit connections between the arithmetic unit and the memory are interrupted if changed process signals have to be input or processed signals have to be output to the process, and a connection is established from the memory to the input / output unit. For these functions, an interrupt unit is necessary »which due to existing conditions

Decision for an "Interrupt" drops and the creation of appropriate circuit connections triggers * Although this interrupt method of operation guarantees maximum processing times, since the arithmetic unit is only interrupted in its work when inputs and outputs are required, but the time between the on - / Output operations are relatively long, so that so that the risk of signal interference is greater because incorrect input and output signals are corrected until the next input / output Vorgarig. During this time, however, subsequent errors may already have occurred due to execution of incorrect .Punctions on the process to be controlled.

Object of the invention

The invention has a programmable circuit with greater security against interference, which can occur on the signal transmission path from the process to the programmable controller part with the aim of additional reduction of the circuit complexity, higher reliability and lower maintenance.

Explanation of the essence of the invention.

The object of the invention is a circuit arrangement for a programmable control device with process coupling, wherein the programmable control device has a computer and a program memory each having an image memory part for input / or output. Output data contains and is connected via an interface and an address bus and an input / output data bus to an input / output unit for process coupling, with the interposition of galvanic decoupling elements to provide in which the inputs and outputs are made in fixed predetermined short time intervals and the input / output unit should be located outside the interference protected area.

According to the invention, this object is achieved in that the programmable controller is controlled by a clock in a repetitive cycle, a first sequence of switching connections between the program memory and the arithmetic unit and a second Polge of connections between the program memory and the input / output - »Unit * contains, with the input / output unit of the programmable controller is arranged spatially separated in the process control cabinet by the input / output data bus and the address bus from the interface is led directly into the non-interference protected process control cabinet and only in these bus lines are connected between interface and input / output unit galvanic decoupling elements.

Preferably, the input / output unit is formed in the process control cabinet at the same time as a distribution circuit for the process lines.

Optocouplers are advantageously used as galvanic decoupling elements, which are connected in the bus lines for the input data before their connection to the interface and in the bus lines for the output data and addresses before their connection to the input / output unit.

embodiment

In the drawing is an embodiment of the invention. shown. It shows a programmable controller with process coupling «.

Of the programmable controller, a computing unit 1 and a read-write memory 2 is shown, which are connected via an address bus 3 with 16 lines and a data bus 4 with 8 lines with each other · The read-write memory 2 includes an image memory part 2.1 for the input signals, an image memory part 2.2 for the output signals and a memory area 2.3 for switching equations ·

and a memory area 2.4 for the control program. The data bus 4 and the address bus 3 lead to an interface circuit 5 j which internally consists of matching circuits 6, 7 and 9. The matching circuit 6 connects the data bus 4 with a process data bus 10 consisting of 8 lines for the output signals, the matching circuit 7 connects the data bus 4 with a likewise consisting of 8 lines process data bus 11 for the input signals and the matching circuit 9 connects the address bus 3 with one of 8 Lines existing Prozeßadreßbus 12. At the interface circuit 5, an optocoupler 13 is interposed in each of the 8 lines of the process data bus 11 for the input signals.

The programmable controller with the described Ankopplung'der process data buses 10, 11 and the Prozeßadreßbus 12 to the control internal data bus 4 and address bus 3 in the interface circuit 5 are housed protected against interference in a common housing 14. The process data buses 10, 11 and the Prozeßadreßbus 12 are led out of this interference-protected housing 14 and directed in a spatially distant in the immediate liahe of the machine tool to be controlled power switch cabinet 15. Each of the 8 lines of the process data buses 10, 11 and the Prozeßadreßbus 12 is connected via amplifiers 17, 18, 19 to an input / output unit 20. In each of the input lines to the amplifier 17 from the process data bus 10 is an optocoupler 21 and in each of the input lines to the amplifier 19 from the Prozeßadreßbus 12 an optocoupler 22 is interposed «The input / output unit 20 includes a number of output distribution circuits 23, 24» 25th and a number of input distribution circuits 26, 27, 28 * from the amplifiers 17 of the Prozeßdatenbus 10 performs for the output signals on the output distribution circuits 23, 24, 25 'to which also the P _r ozeßadreß.bus 12 is connected, "

208 5

The input distribution circuits 26, 27, 28 are connected to the process data bus 11 for the input signals and are also located on the process address bus 12.

Each of the output 3 distribution circuits 23, 24, 25 has 8 output lines, and each of the input distribution circuits 26, 27, 28 has 8 input lines. This Ausgangsbzw. Eingangsleiturcgen are directly connected to the process switching elements in the power switching cabinet 15 and on the machine tool. The output and input distribution circuits 23 to 28 include flip-flops as signal-storing elements. ,

The mode of operation of the programmable control device according to the invention with process coupling is the following:

The arithmetic unit 1 takes, in accordance with the control program stored in the memory area 2.4 of the read-write memory 2, the input signals in the image memory part 2.1 from the process and processes them according to the stored in the memory area 2.3 switching equations. The results are transmitted to the image memory part 2.2 and are there as output signals for the process to be controlled ready. The respective call of the image memory parts 2.1, 2.2 or the memory areas 2.3, 2.4 via the address bus 3 «The data transfer between read-write memory 2 and arithmetic unit 1 via the data bus The control program contains a fixed sequence of operations, which from a clock is controlled. The correspondence between the arithmetic unit 1 and the read-write memory 2 takes place on the basis of a first sequence of switching connections, and the on-output of the process signals is realized by a second series of switching connections. In this case, the image memory part 2.1 for the input signals and the image memory part 2.2 for the Ausgangssigna.le via the data bus 4 and the process data buses 10, 11 are connected to the input / output unit 20.

The control program 2.4 processes these "two poles of interconnections in the form of a fixed sequence of operations which are constantly repeated, the input of the process input signals into the image memory section 2.1 of the random access memory 2 and the output of the output signals from the image memory section 2.2 the process takes place by blocking the connections from the read-write memory 2 to the arithmetic unit 1 and activating the connections of the image memory parts 2.1, 2.2 with the input / output unit 20 by calling the respective input / output distributor circuit 23 to 28.

This is done in such a way that the control program 2.4 via the address bus 3, the An¬ in the interface circuit 5 An 'mating circuit 6 controls and thus the output signals via the process data bus 10, the optocoupler 21, the amplifier 17 to one of the output distribution circuits 23rd or 24 or 25 in the input / output unit 20 transmits. The output distribution circuits 23, 24 _s 25 are called by the control program 2.4 via the address bus 3 »the matching circuit.9, the Prozeßadreßbus 12, the optocoupler 22 and the amplifier 19, so that the image memory part 2,2 standing in the output signals associated with the flip Flops in the output distribution circuits 23, 24, 25 set.

Hach output of the last output signal from the last memory location of the image memory section 2.2, the control program 2.4 addresses the matching circuit 7 in the interface circuit 5 for the input data. In the matching circuit 9 is via the address bus 3 and the data bus 4, the respective input distribution circuit 26 or 27 or «. 28, in which it is called up via the program data bus 12, the optocouplers 22 and the amplifiers 19 *

The input distribution circuits 26, 27, 28 are called successively and input the input signals stored in their flip-flops via the amplifiers 18, the process data bus 11, the optocouplers 13, the matching circuit 7 and the data bus 4

to the image memory part 2.1, the memory locations are activated in the same order, so that the image of the input signals from the process in the random access memory 2 is taken.

By, this cyclic operation, a minimal amount of circuitry is required because the interruption and the associated associated circuit measures omitted. The cyclic operation also allows a high noise immunity, because at intervals of about 10 ms, the input / output operations are repeated, so that occurring in an input or output error signals can not affect the process, because the to be addressed electromagnetic contactors, Valves U. a. On the other hand, they have high response times and therefore do not respond yet. However, before these components switch, the input / output process has already repeated, eliminating the errors previously caused by external disturbance influences. Due to this favorable effect, disturbances which briefly occur on the input / output unit 20 and the process data buses 10, 11 or the process address bus 12 are rendered harmless, so that the input / output unit 20 can be arranged in the power storage cabinet 15 and the process data buses 10, 11 and the Prozeßadreßbus 12 can also be out of the interference-protected housing 14 out into the power switch cabinet 15. Also the otherwise necessary measures for debouncing the input signals are no longer necessary.

These process data buses 10, 11 and the Prozeßadreßbus 12 consist of little pipes (8 lines) _s which only in the A '/ output unit be expanded to the required number of process connections., Thus, the cable connection between the containing the programmable controller housing 14 and the power switch cabinet 15 limited to little cable, and

equally the cost of the necessary optocoupler 13 »21, 22 limited to the same small number (per 8 optocouplers per data« or address bus) * In addition eliminates in Starkstromschaltsohrank 15 otherwise required additional distribution circuit. The process connections are located directly on the input / output unit 20 and are already clamped so that the distributor function is met «, also eliminates connectors, which further reduce the assembly work and Y / artungsaufwand. Overall, a simple, clear process connection to a programmable controller has been provided which, in conjunction with the cyclic operation of input / output, ensures high reliability and low maintenance.

Claims (3)

invention claim 1 # Circuit arrangement for a programmable control device with process connection, wherein the programmable control device has an arithmetic unit and a program memory each having an image memory part for input / or output. Contains output data and is connected via an interface and an address bus and an input / output data bus to an input / output unit for the process connection, with the interposition of galvanic decoupling elements, in particular for machine tool controls, characterized in that the programmable controller is controllable by a clock in a repeating cycle containing a first sequence of interconnections between the program memory and the arithmetic unit and a second series of interconnections between the program memory and the input / output unit, the input / output unit is arranged spatially separated from the programmable controller in the process control cabinet by the input / output data bus and the address bus from the interface is led directly into the non-interference protected process control cabinet and galvanic decoupling elements are connected only in these bus lines between interface and input / output unit 2, circuit arrangement according to item 1,
characterized,. that the input / output unit is formed in the process control cabinet at the same time as a distribution circuit for the process lines. 3 »Circuit arrangement according to Pkt. 1 and 2, characterized in that optocouplers are used as galvanic decoupling elements which are connected in the bus lines for the input data before their connection to the interface and in the bus lines for the output data and addresses before their connection to the input / output unit. lierzu ^ page. drawings