GB2403051A - Logic controller programming system - Google Patents
Logic controller programming system Download PDFInfo
- Publication number
- GB2403051A GB2403051A GB0314003A GB0314003A GB2403051A GB 2403051 A GB2403051 A GB 2403051A GB 0314003 A GB0314003 A GB 0314003A GB 0314003 A GB0314003 A GB 0314003A GB 2403051 A GB2403051 A GB 2403051A
- Authority
- GB
- United Kingdom
- Prior art keywords
- instructions
- memory chip
- safety circuit
- plc
- programming
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 238000010200 validation analysis Methods 0.000 claims abstract description 15
- 238000012546 transfer Methods 0.000 claims abstract description 9
- 238000000034 method Methods 0.000 claims description 19
- 238000013461 design Methods 0.000 claims description 13
- 238000012360 testing method Methods 0.000 claims description 8
- 230000005540 biological transmission Effects 0.000 claims description 2
- 230000006870 function Effects 0.000 description 5
- 238000013459 approach Methods 0.000 description 2
- 230000005856 abnormality Effects 0.000 description 1
- 230000003466 anti-cipated effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 230000007257 malfunction Effects 0.000 description 1
- 230000008672 reprogramming Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B19/00—Programme-control systems
- G05B19/02—Programme-control systems electric
- G05B19/04—Programme control other than numerical control, i.e. in sequence controllers or logic controllers
- G05B19/05—Programmable logic controllers, e.g. simulating logic interconnections of signals according to ladder diagrams or function charts
- G05B19/056—Programming the PLC
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B19/00—Programme-control systems
- G05B19/02—Programme-control systems electric
- G05B19/04—Programme control other than numerical control, i.e. in sequence controllers or logic controllers
- G05B19/048—Monitoring; Safety
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B2219/00—Program-control systems
- G05B2219/10—Plc systems
- G05B2219/13—Plc programming
- G05B2219/13024—Convert digital logic of hardware circuit into plc software
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B2219/00—Program-control systems
- G05B2219/10—Plc systems
- G05B2219/13—Plc programming
- G05B2219/13185—Software function module for simulation
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Automation & Control Theory (AREA)
- Programmable Controllers (AREA)
Abstract
A safety circuit arrangement for electrical equipment, electromechanical machinery, or the like comprises a programmable logic controller (PLC) (7) fitted with a replaceable read-only memory (ROM) chip (6a) containing instructions to cause the PLC (7) to operate to simulate a desired hardwired safety circuit. These instructions are installed into the ROM chip (6) using a chip programming unit (5) controlled by a computer (1). The computer (1) is programmed to allow a user to build up a representation of the desired safety circuit on screen (2) and to convert the circuit so represented to instructions for the PLC (7) to simulate that circuit. The simulated safety circuit may be tested to see whether it operates as desired, either by the computer (1) prior to transfer of the instructions to the chip (6), or by a separate validation unit into which the chip (6) is inserted prior to being fitted to the PLC (7). The PLC (7) may only be reprogrammed by removing a first chip (6a) and replacing it with a second chip (6a) bearing different instructions.
Description
240305 1
LOGIC CONTROLLER PROGRAMMING SYSTEM
The present invention relates to a system for instructing a programmable logic controller by means of transferable memory chips or the like. More particularly, but not exclusively, it relates to a system and method for programming transferable memory chips to instruct a programmable logic controller to act as a safety device i-or electrical equipment.
It is generally advisable for electrically powered or controlled machinery to be provided with safety circuitry, adapted to modify or interrupt the operation of the machinery in case of a fault. Such faults can include physical or electrical malfunctions in the machinery itself, abnormalities in its power supply, or a too close approach of an operator or passer-by to dangerous parts of the machinery.
In its conventional iorm, such safety circuitry may be assembled by a competent electrician or the like, using a metaphorical or actual toolbox of standard electrical components, for example relays of varying complexity and timer/delay circuits. Where the range of potential fault conditions and/or the range of possible outcomes is larger, the electrician may be able to wire together an arrangement of standard components to perform the required function.
However, there are limitations in this approach.
It has been found that with the complexity required for the safety systems of much modern machinery, it is very difficult to assemble a suitable safety circuit from separate standard components. Not only is it conceptually difficult to put together the correct components and ensure that they interact as desired, but the resulting arrangement of components may be excessively bulky and even physically difficult to wire together correctly. It would therefore be desirable to use a compact electronic system performing the same functions as a conventional electrical/electromechanical safety system.
A conventional programmable logic controller (PLC) might be considered suitable, but PLC programming is known to be a specialist skill. Thus, no attempts appear to have been made to use PLCs in such applications.
It is also essential that a safety system is genuinely safe under any fault condition that it is likely to meet. It would be preferable if this could be confirmed before the safety system is actually in operation.
PLCs have become available which may be programmed or instructed via replaceable memory modules or chips. I hose have the benefit that in the case of failure, a replacement memory chip can be inserted in the existing PLC, or a current memory chip can be transferred Lo a replacement for a failed PLC, as appropriate - no lengthy reprogramming is required. Such PLCs may be of particular use in the present invention.
It is hence an object of the present invention to provide a system and a method for programming a memory chip to control a programmable logic controller to act as a safety system. It is also an object of the present invention to provide a programmable logic controller adapted to act as a safety system.
According to a first aspect ol the present invention, there is provided a system for programming memory chip means with instructions to cause a programmable logic controller (PLC) to simulate a desired safety circuit, the system comprising computing means provided with display means and data input means, and programming means adapted to transfer said instructions to the memory chip means, wherein the computing means is programmed to permit employment of the data input means to display said desired safety circuit on the display means and automatically to generate said instructions from the structure of the safety circuit so displayed.
Preferably, the system comprises validation means to check that said instructions would cause a PLC to respond as desired to selected input stimuli, such as fault conditions.
Advantageously, said validation means comprises an element of a software program running on the computing means.
Alternatively or additionally, the validation means may comprise a validation unit into which said memory chip means may be inserted following transfer of the instructions thereto.
The computing means may be directly connected to the programming means.
Alternatively, the instructions may be transferred from the computing means to the programming means on portable data carrier means, such as a magnetically or optically readable data disc.
The memory chip means preferably comprises read-only memory (ROM) chip means.
The instructions transferred to the memory chip means may then not be amended or corrupted once they have been transferred thereto.
According to a second aspect of the present invention, there is provided a method for programming a Pl,C with instructions to cause it to simulate a desired safety circuit, comprising the steps of providing each of computing means, memory chip means operably insertable into the PLC and programming means for said memory chip means, inputting a design for the desired safety circuit into the computing means, generating said instructions from said design, transmitting the instructions via the programming means to the memory chip means, and transferring the memory chip means to the PLC.
Preferably, the method comprises the step of testing said instructions prior to transfer of the memory chip means to the P1,C to ensure that they would cause the Pl,C to behave as desired.
Advantageously, the method comprises the steps of providing a validation device into which the memory chip means is operably insertable and performing said testing step using the validation device.
Alternatively or additionally, the method comprises performing said testing step within the computing means prior to transmission of the instructions to the memory chip means.
I'he method may also comprise the steps of removing from the PLC first memory chip means carrying a first set of said instructions and inserting into the PLC in its place second memory chip means carrying a second set of instructions different from the first.
According to a third aspect of the present invention, there is provided safety circuit means comprising a programmable logic controller provided with replaceable memory chip means, wherein the memory chip means carries instructions to cause the programmable logic controller to respond to input signals as would a pre-selected safety circuit.
Preferably, the safety circuit means comprises at least two said programmable logic controllers, each provided with memory chip means carrying identical said instructions and operating in parallel each with the others.
I'he safety circuit means may then be provided with means to exchange data between the programmable logic controllers such that each may monitor the operation of the others.
The at least two programmable logic controllers may comprise an integral unit.
Advantageously, the or each memory chip means may comprise memory chip means programmed by a system as described in the first aspect above, and/or programmed according to a method as described in the second aspect above.
Preferably, the memory chip means comprises read-only memory (ROM) chip means.
The safety circuit means may then only be provided alternative or modified instructions by replacing first memory chip means carrying a first set of instructions with second memory chip means carrying said alternative or modified instructions.
An embodiment ot the present invention will now be more particularly described by way of example and with reference to the accompanying drawings, in which: Figure I shows schematically a chip programming system embodying the invention; and Figure 2 shows the more important elements of a screen display of the system of Figure 1.
Referring now to the figures and to Figure I in particular, a chip programming system comprises a computer I provided with a conventional display screen 2 and conventional keyboard 3 and mouse 4 input devices. The computer 1 is operatively connected to a chip programming unit 5, into which is removably inserted a memory chip 6 for a programmable logic controller (PLC). (In alternative embodiments, the computer I and chip programming unit 5 may in effect be linked by transferring files on floppy disc, CD-ROM or other transferable data carrier, rather than having a directly wired connection as shown).
Using a method described more tully below, the computer 1 generates a set of instructions, in an appropriate format, to cause a PLC to behave as a specific desired safety circuit. The computer I transfers these instructions to the chip programming unit 5, which writes them on to the memory chip 6.
The memory chip 6a is then transferred to a PLC 7 connected to a control circuit for a piece of machinery (not shown). The PLC 7 then simulates the operation of the desired safety circuit, responding appropriately to the various fault conditions that it may encounter.
In an alternative embodiment, not shown, the Pl,C 7 is provided with two identical memory chips 6a and operates as two parallel safety circuits, each of which monitors the operation of the other, for added safety.
Each memory chip 6, 6a should, for safety and reliability, be a ROM (readonly memory) chip. l bus, once the memory chip 6a is in place in the PLC 7, the instructions that it carries cannot be altered or corrupted.
A conventional form of PLC with a RAM (random access memory) could have its instructions altered locally, which might be undesirable for safety or security reasons. A ROM chip 6, 6a has its instructions "burnt" on to it only once. To change the instructions for the PLC 7, a replacement ROM chip 6, 6a must be installed, carrying the desired new set of instructions. (The original chip 6, 6a may be stored in case the instructions carried thereon may be needed again) The ROM chip 6, 6a is also not susceptible to having its instructions corrupted or deleted by an electrical "spike", unlike the "volatile" memory of a conventional RAM.
The computer I is programmed with software which permits an operator with a knowledge of conventional relay circuit design to enter a conventional circuit design, simple or highly complex, using conventional input devices 3, 4. The principles of this software will be described with reference to a typical screen 2 display, as shown in Figure 2.
Using keyboard 3 and/or mouse 4 commands, an operator builds up a safety relay circuit design 8 on the screen 2, in the l'ormat conventionally referred to as a ladder diagram. This format allows convenient two dimensional display of a circuit which may be considerably more complex, although it does not necessarily directly relate to the geometry of the physical circuit (for example, each box 9, referred to as an output function, may in reality represent a connection back to another part of the design 8). Beyond a certain level of complexity, it clearly becomes difficult to build the corresponding physical circuit and wire up all the necessary interconnections. It also becomes almost impossible to check that the physical circuit would actually perform as planned, without building and testing it in action.
The operator builds up the design 8 using a first menu 10 of icons representing "contact strings" and a second menu 11 of icons representing "output functions", each of which may be placed, for example by "drag and drop" manipulation with the mouse 4, in a desired one of an array of vacant fields 12 provided on the screen 2. Alphanumeric identifiers 13 are then inserted adjacent the icons to indicate where each output function box 9 links back to a contact string elsewhere in the design 8. Once the operator is satisfied that the design 8 is complete, he commands the computer I to calculate an instruction set for the PLC 7 (in a programming language to which the PL,C 7 responds) equivalent to the design 8 and to transfer this to the chip programming unit 5, which writes it on to the chip 6.
The software package on the computer 1 checks that the circuit design 8 is actually possible and would operate. In a first version of the system, the software package allows the operator to test on-screen how the circuit would respond to selected stimuli, including anticipated fault conditions.
Alternatively or additionally, the system may also comprise a validation unit (not shown), into which a memory chip 6 may be inserted before it is transferred to the PLC 7. The validation unit with the memory chip 6 in place acts as a PLC, simulating the PLC 7 of the safety circuit. It is provided with switches to allow signals to be sent to selected input channels, and indicator lights linked to each output channel to show whether a PLC operating according to the instruction set on the memory chip 6 would behave as planned.
Thus, a complex, possibly physically unbuildable, safety relay circuit can be designed on- screen, an instruction set to cause a PLC to simulate that circuit can be generated, the effectiveness oi the circuit can be tested, and then a memory chip carrying a validated set of instructions can be inserted into a PLC linked to a piece of machinery, etc. which will proceed to act as if it were the circuit in question.
Not only does this allow very complex safety circuits to be designed and used, that would not be practical with conventional physical components, but also these circuits can be thoroughly tested before being put into operation. No specialist knowledge of PLC programming languages or techniques is required.
The chip used in this invention is therefore effectively a piece of hardware. It cannot be corrupted by electrical interference, nor by misuse or operator error. This incorruptibility is particularly important in safety systems. It also improves the security and ease of maintenance of the system.
If the system needs to be updated, a new chip can be produced and inserted physically into the system. I lowever, any previous chip can be reintroduced to operate under a previous set of standards.
The system is therefore as secure and reliable as a "hard-wired" safety circuit, but affords far more flexibility and versatility.
Claims (22)
1. Apparatus for programming memory chip means with instructions to cause a programmable logic controller (PLC) to simulate a desired safety circuit, the apparatus comprising computing means having display means and data input means, and programmed to permit employment of the data input means to display said desired safety circuit on the display means and automatically to generate said instructions from the structure of the safety circuit so displayed, and programming means adapted to transfer said instructions to the memory chip means.
2. Apparatus as claimed in claim I comprising validation means to check that said instructions would cause a PLC to respond as desired to selected input stimuli, such as fault conditions.
3. Apparatus as claimed in claim 2, wherein said validation means comprises an element of a software program running on the computing means.
4. Apparatus as claimed in claim 2, wherein the validation means comprises a validation unit into which said memory chip means may be inserted following transfer of the instructions thereto.
5. Apparatus as claimed in any one of claims I to 4, wherein the memory chip means is so adapted that said instructions may not be amended or corrupted once they have been transferred thereto.
6. Apparatus as claimed in any one of claims 1 to 5, wherein the memory chip means comprises read-only memory (ROM) chip means.
7. Apparatus for programming memory chip means substantially as described herein and with reference to the accompanying drawings.
8. A method for programming a PLC with instructions to cause it to simulate a desired safety circuit, comprising the steps ol providing each of computing means, memory chip means operably insertable into the PLC and programming means for said memory chip means, inputting a design for the desired safety circuit into the computing means, generating said instructions from said design, transmitting the instructions via the programming means to the memory chip means, and transferring the memory chip means to the PLC.
9. A method as claimed in claim 8, comprising the step of testing said instructions prior to transfer of the memory chip means to the Pl,C to ensure that they would cause the PLC to behave as desired.
10. A method as claimed in claim 9, comprising the steps of providing a validation device into which the memory chip means is operably insertable and performing said testing step using the validation device.
ll.A method as claimed in either claim 9 or claim 10, comprising performing said testing step within the computing means prior to transmission of the instructions to the memory chip means. I
12. A method as claimed in any one of claims 8 to I 1, comprising the steps of removing t from the PLC first memory chip means carrying a first set of said instructions and inserting into the PLC in its place second memory chip means carrying a second set of instructions different from the first. I
13. A method for programming a PLC substantially as described herein and with reference to the accompanying figures.
14. A method for simulating a desired safety circuit, comprising the steps of providing a PLC, connecting it to equipment to be monitored and/or controlled by the safety circuit, and programming the Pl,C by a method as claimed in any one of claims 8 to 1
15. Safety circuit means comprising a programmable logic controller provided with replaceable memory chip means, wherein the memory chip means carries instructions to cause the programmable logic controller to respond to input signals as would a predetermined safety circuit.
16. Safety circuit means as claimed in claim 15, comprising at least two said programmable logic controllers, each provided with memory chip means carrying identical said instructions and each operating in parallel with the others.
17. Safety circuit means as claimed in claim 16, provided with means to exchange data between the at least two programmable logic controllers such that each may monitor the operation of the others.
18. Safety circuit means as claimed in either claim 16 or claim 17, wherein the at least two programmable logic controllers comprise an integral unit. !
19. Safety circuit means as claimed in any one of claims 15 to 18, wherein the or each I memory chip means comprises memory chip means programmed by apparatus as claimed in any one of claims I to 7, and/or programmed according to a method as claimed in any one of claims 8 to 13.
20. Safety circuit means as claimed in any one of claims 15 to 19, wherein the memory chip means comprises read-only memory (ROM) chip means.
21. Safety circuit means as claimed in any one of claims 15 to 20, adapted to be provided with alternative or modified instructions solely by replacing first memory chip means carrying a first set of instructions with second memory chip means carrying said alternative or modified instructions.
22. Safety circuit means substantially as described herein and with reference to the Figures of the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0314003A GB2403051A (en) | 2003-06-17 | 2003-06-17 | Logic controller programming system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0314003A GB2403051A (en) | 2003-06-17 | 2003-06-17 | Logic controller programming system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB0314003D0 GB0314003D0 (en) | 2003-07-23 |
| GB2403051A true GB2403051A (en) | 2004-12-22 |
Family
ID=27636701
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB0314003A Withdrawn GB2403051A (en) | 2003-06-17 | 2003-06-17 | Logic controller programming system |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2403051A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1986063A3 (en) * | 2007-04-27 | 2009-08-05 | OMRON Corporation, a corporation of Japan | Simulation device for programmable controller |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20020040286A1 (en) * | 2000-10-02 | 2002-04-04 | Akihiro Inoko | PLC system construction support tool and PLC system program development support tool including the same |
| US6549034B1 (en) * | 2001-12-27 | 2003-04-15 | Rockwell Automation Technologies, Inc. | Programmable logic controller for safety systems with reduced cross-wiring |
-
2003
- 2003-06-17 GB GB0314003A patent/GB2403051A/en not_active Withdrawn
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20020040286A1 (en) * | 2000-10-02 | 2002-04-04 | Akihiro Inoko | PLC system construction support tool and PLC system program development support tool including the same |
| US6549034B1 (en) * | 2001-12-27 | 2003-04-15 | Rockwell Automation Technologies, Inc. | Programmable logic controller for safety systems with reduced cross-wiring |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1986063A3 (en) * | 2007-04-27 | 2009-08-05 | OMRON Corporation, a corporation of Japan | Simulation device for programmable controller |
| CN101295173B (en) * | 2007-04-27 | 2011-01-19 | 欧姆龙株式会社 | Simulation device for programmable controller |
| US7974828B2 (en) | 2007-04-27 | 2011-07-05 | Omron Corporation | Simulation device for programmable controller |
Also Published As
| Publication number | Publication date |
|---|---|
| GB0314003D0 (en) | 2003-07-23 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |