CA2036013A1 - Apparatus for the fail-safe display of an indicating diagram - Google Patents
Apparatus for the fail-safe display of an indicating diagramInfo
- Publication number
- CA2036013A1 CA2036013A1 CA002036013A CA2036013A CA2036013A1 CA 2036013 A1 CA2036013 A1 CA 2036013A1 CA 002036013 A CA002036013 A CA 002036013A CA 2036013 A CA2036013 A CA 2036013A CA 2036013 A1 CA2036013 A1 CA 2036013A1
- Authority
- CA
- Canada
- Prior art keywords
- memory
- code
- screen
- check
- check code
- 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.)
- Abandoned
Links
Classifications
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F11/00—Error detection; Error correction; Monitoring
- G06F11/07—Responding to the occurrence of a fault, e.g. fault tolerance
- G06F11/16—Error detection or correction of the data by redundancy in hardware
- G06F11/1608—Error detection by comparing the output signals of redundant hardware
- G06F11/1616—Error detection by comparing the output signals of redundant hardware where the redundant component is an I/O device or an adapter therefor
- G06F11/162—Displays
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F11/00—Error detection; Error correction; Monitoring
- G06F11/07—Responding to the occurrence of a fault, e.g. fault tolerance
- G06F11/0703—Error or fault processing not based on redundancy, i.e. by taking additional measures to deal with the error or fault not making use of redundancy in operation, in hardware, or in data representation
- G06F11/0751—Error or fault detection not based on redundancy
- G06F11/0763—Error or fault detection not based on redundancy by bit configuration check, e.g. of formats or tags
Landscapes
- Engineering & Computer Science (AREA)
- Theoretical Computer Science (AREA)
- Quality & Reliability (AREA)
- Physics & Mathematics (AREA)
- General Engineering & Computer Science (AREA)
- General Physics & Mathematics (AREA)
- Controls And Circuits For Display Device (AREA)
- Digital Computer Display Output (AREA)
- Fittings On The Vehicle Exterior For Carrying Loads, And Devices For Holding Or Mounting Articles (AREA)
- Alarm Systems (AREA)
- Detection And Correction Of Errors (AREA)
- Control Of Indicators Other Than Cathode Ray Tubes (AREA)
Abstract
Abstract Apparatus for the Fail-Safe Display of an Indicating Diagram An apparatus for the fail-safe display of an indicating diagram is disclosed which allows the use of high-resolution screens (HB) with individually addressable dots and eliminates the need to derive a check code from the serial picture-data stream, which derivation poses problems at very high refresh memory readout fre-quencies. To generate the check code, the picture data which are transferred into the refresh memory (BW1) are transferred in parallel into an additional, like memory (BW2) which is not followed by a screen, and read immediately thereafter from the additional memory into a check-code generator (P). In a control computer (SR) calling for the indicating-diagram display, a check code generated by the check-code generator is compared with a previously stored reference code. If the two codes do not match, an error indication is initiated.
Figure K. Pierick et al 1-1-2-2
Figure K. Pierick et al 1-1-2-2
Description
2~336~1e~
~ 1 -Apparatus for the Fa;l-Safe Display of an Indicating Diagram The present invention relates to an apparatus as set forth in the preamble of claim 1. Such an apparatus is described in DE 34 11 015 A1~
In the prior art apparatus, safety of the screen di.splay is ach;eved by deriving~ in a feedback shi~t register, a check code from the serial data stream applied to the screen, and comparing this check code with a previously determined and stored reference code assigned to the respective indicating diagram. To reduce the storage space requ;red to store the reference code for the many possible indicating-diagram variations~ the refer-ence code is composed of a basic code for an indicating diagram containing the static picture eLements and a change code For the individual possible changes ;n the indicating diagram.
If use is made of high-resolution screens whose re-fresh memories are addressed and read out dot by dot~
the amount oF data to be transferred and, hence, the frequency necessary for the serial transfer of the data becomes so high that data reduct;on by means of a -Feed-back shift reg;ster for form;ng the check code poses problems.
K. Pierick et al 1-1-2-2 2~)36~)~3 It is, therefore, the object of the invention to pro-vide an apparatus of the aboue kind wh;ch can be used together with a high-resolution screen.
This object is a~tained by the features set forth in the characterizing part of claim 1.
The use of a second refresh memory whose contents are not displayed on the screen makes it possi:ble to check the correct functioning of the screen controller during the conversion of all possible code words of the control computer into the picture elements assigned to these code words.
Since it is not the fast serial data stream directed to-ward the screen which is evaluated, but memory contents, which remain unchanged for a protracted period of time, there are no time problems during the formation of the check code and during the subsequent comparing process.
A circumstance which, if use were made of refresh memories which are not addressed dot by dot, would in-volve a safety risk is that the Fefresh memory necessary for the screen display would not be checked.
If, however, memories with individually selectable celLs each assigned to a single dot are employed, this circumstance represents no safety risk, since one or more individual dots wh;ch are not addressed or are addressed in a wrong color due to component failures cannot change the optical impression of a picture element~ consisting of, e.g., many hundred K. Pierick et al 1-~-2 2 - 3 - ~ ~3 dots, to the point that the picture element is no longer discernable or will be confused w;th another p;cture element~ Any fa;lure of the entire refresh memory due to, e.g., a fault ;n its power supply results in a drop-out of the entire image of the indicating d;agram and w;ll thus be detected in any case.
Aduantageous features of the applaratus according to the ;nvent;on are defined in the subcla;ms. The subject matter of cla;m 2 takes advantage of the fact that commerc;ally ava;lable visual display units equipped with high-resolut;on color d;splays use memor;es of "square design", i.e., memor;es hav;ny just as many rows as columns9 whose storage space~ because of the rectangular des;gn of the screens, rema;ns partly un-used, ;ue.~ ;nformation stored there doesnotappear on the screenu The p;cture data to be checked can thus be -subjected to a coord;nate d;splacement or stored ;n the otherw;se unused area of the refresh memory w;thout appearing on the screen. This el;minates the need for a special second memory.
The subject matter of cla;m 3 makes it possible to check, in addition to the picture data o-f the picture elements being displayed on the screen, the picture data of those p;cture elements which do not appear simultaneously on the screen. In this fashion a problem is solved which ;s very important for the availability of the apparatus according to the invention:
If only picture data are checked which are displayed K. P;er;ck et al 1-1-2-2 ~C136;~
-- 4 ~
simultaneously on the screen, only those components or program parts of the screen controller will be checked wh;ch are needed for the respective picture represen-tation called for by the control computer. Circuit or program parts which are not needed are not checked. As a result, an error will be detected only if a picture called for can be displayed e;ther not at all or only without fail-safety, so that the error has already re-sulted in a restriction of opera~tions.
In the case of rarely requested picture elements, the time until the detection of an error may then become so long that the probability of the occurrence of a dangerous double error is no longer negligibly small, so that the corresponding p;cture element must be called up outside the normal operation, within a check routine to be performed at regular time intervals.
The subject matter of claim 3 el;m;nates the need for such special measures.
Ciaim 4 pro~ides for the use of a control computer as a comparing circuit and thus eliminates the need for a special Gomparing circuit.
An embodiment of the apparatus according to the in~en-tion will now be described in detail w;th reference to the accompanying drawing.
The single figure of the drawing shows a block diagram with a high-resolut;on screen HB wh;ch is addressed dot by dot by a screen controller BA~ In a first refresh memory BW1, each dot of the screen is assigned one cell K. Pierick et al 1-1-2-2 ~(~3~ 3 ~ 5 for each primary color. The state of this cell is trans-ferred over a high-speed serial bus -to the image-~orming system of the screen~ Each cell of the refresh memory ;s selected ;ndividually and independerltly from a computer CPU over a parallel bus" said computer being contained in the screen controller or in the refresh-memory module~ The compu~ter generates the respective dot combination in accordance with a code word transferred to ;t over a control l;ne SL, wh;ch ;s operated in a fail-safe mode, e~g.~ a two-channel mode, from a fa;l-safe control computer (SR),consist;ng in th;s embod;ment of two separate computers R1, R2 operat;ng in a parallel mode wh;ch compare the results created by them~
Depend;ng on the code word appl;ed~ the computer in the screen controller w;thdraws the informat;on assigned to the code word from a read-only memory or performs given program steps which resuLt in the, e.g~, vector-graphic creation of the p;cture data assoc;ated w;th the picture element determined by the code word~
S;multaneously with the transFer of these picture data into -the f;rst refresh memory BW1, these data are trans-ferred into a second refresh memory B~2 which is not followed by a screen. There they remain stored as ~ong as the associated p;cture element ;s visible on the screena During the time that the picture data are re-peatedly read From the first refresh memory and dis-played on the screen, the picture data stored in the second K. Pierick et al 1-1-2-2 36~3 refresh memory are read back into the computer CPU and fed to a check-code generator P for generating a characterist;c check code. This check-code generator, l;ke in the prior art, may include a -feedback register, but it may also include a subroutine of the computer CPU contalned in the screen controller.
The check code is transferred over the control line SL
to the check computer SR and compared by the latter with a reference check code stored for each code word from the screen controller ;n a memory (not shown) of the control computer.
Instead of storing the picture data in a second refresh memory, the picture data can be stored in a port;on of the first refresh memory which is not used for the screen display. The second refresh memory BW2 can then be dispensed with. If two or more screens are to be supplied with picture data from the screen controller, further refresh memories may be pro~ided. One refresh memory may then be used by all screens as the second refresh memory.
If the computer of the screen controller is programmed so as to be able to load the second refresh memory BW2 with picture data independently of the f;rst refresh memory BW1, which supplies the screenj it ;s possible to additionally check the creation of those picture data whirh are associated with a picture element that must not appear on the screen at that time~ Thus, the creation of picture elements to be displayed uery K. Pierick et al 1-1-2-2 36~)~3 rareLy, such as the symbol for a switch-trail;ng message in a railway si0naLling system, can be checked without a service interruption~ The picture data created only for checkiny purposes are generated if the code word outputted by the control computer in-cludes a spec;al check flag. The picture data created in response to such a code word are also marked as check data and, because of this marking, can only be entered into the second refresh memory~ so that any unintentional display of these check data on the screen is excluded.
K~ Pierick et al 1-1-2-2
~ 1 -Apparatus for the Fa;l-Safe Display of an Indicating Diagram The present invention relates to an apparatus as set forth in the preamble of claim 1. Such an apparatus is described in DE 34 11 015 A1~
In the prior art apparatus, safety of the screen di.splay is ach;eved by deriving~ in a feedback shi~t register, a check code from the serial data stream applied to the screen, and comparing this check code with a previously determined and stored reference code assigned to the respective indicating diagram. To reduce the storage space requ;red to store the reference code for the many possible indicating-diagram variations~ the refer-ence code is composed of a basic code for an indicating diagram containing the static picture eLements and a change code For the individual possible changes ;n the indicating diagram.
If use is made of high-resolution screens whose re-fresh memories are addressed and read out dot by dot~
the amount oF data to be transferred and, hence, the frequency necessary for the serial transfer of the data becomes so high that data reduct;on by means of a -Feed-back shift reg;ster for form;ng the check code poses problems.
K. Pierick et al 1-1-2-2 2~)36~)~3 It is, therefore, the object of the invention to pro-vide an apparatus of the aboue kind wh;ch can be used together with a high-resolution screen.
This object is a~tained by the features set forth in the characterizing part of claim 1.
The use of a second refresh memory whose contents are not displayed on the screen makes it possi:ble to check the correct functioning of the screen controller during the conversion of all possible code words of the control computer into the picture elements assigned to these code words.
Since it is not the fast serial data stream directed to-ward the screen which is evaluated, but memory contents, which remain unchanged for a protracted period of time, there are no time problems during the formation of the check code and during the subsequent comparing process.
A circumstance which, if use were made of refresh memories which are not addressed dot by dot, would in-volve a safety risk is that the Fefresh memory necessary for the screen display would not be checked.
If, however, memories with individually selectable celLs each assigned to a single dot are employed, this circumstance represents no safety risk, since one or more individual dots wh;ch are not addressed or are addressed in a wrong color due to component failures cannot change the optical impression of a picture element~ consisting of, e.g., many hundred K. Pierick et al 1-~-2 2 - 3 - ~ ~3 dots, to the point that the picture element is no longer discernable or will be confused w;th another p;cture element~ Any fa;lure of the entire refresh memory due to, e.g., a fault ;n its power supply results in a drop-out of the entire image of the indicating d;agram and w;ll thus be detected in any case.
Aduantageous features of the applaratus according to the ;nvent;on are defined in the subcla;ms. The subject matter of cla;m 2 takes advantage of the fact that commerc;ally ava;lable visual display units equipped with high-resolut;on color d;splays use memor;es of "square design", i.e., memor;es hav;ny just as many rows as columns9 whose storage space~ because of the rectangular des;gn of the screens, rema;ns partly un-used, ;ue.~ ;nformation stored there doesnotappear on the screenu The p;cture data to be checked can thus be -subjected to a coord;nate d;splacement or stored ;n the otherw;se unused area of the refresh memory w;thout appearing on the screen. This el;minates the need for a special second memory.
The subject matter of cla;m 3 makes it possible to check, in addition to the picture data o-f the picture elements being displayed on the screen, the picture data of those p;cture elements which do not appear simultaneously on the screen. In this fashion a problem is solved which ;s very important for the availability of the apparatus according to the invention:
If only picture data are checked which are displayed K. P;er;ck et al 1-1-2-2 ~C136;~
-- 4 ~
simultaneously on the screen, only those components or program parts of the screen controller will be checked wh;ch are needed for the respective picture represen-tation called for by the control computer. Circuit or program parts which are not needed are not checked. As a result, an error will be detected only if a picture called for can be displayed e;ther not at all or only without fail-safety, so that the error has already re-sulted in a restriction of opera~tions.
In the case of rarely requested picture elements, the time until the detection of an error may then become so long that the probability of the occurrence of a dangerous double error is no longer negligibly small, so that the corresponding p;cture element must be called up outside the normal operation, within a check routine to be performed at regular time intervals.
The subject matter of claim 3 el;m;nates the need for such special measures.
Ciaim 4 pro~ides for the use of a control computer as a comparing circuit and thus eliminates the need for a special Gomparing circuit.
An embodiment of the apparatus according to the in~en-tion will now be described in detail w;th reference to the accompanying drawing.
The single figure of the drawing shows a block diagram with a high-resolut;on screen HB wh;ch is addressed dot by dot by a screen controller BA~ In a first refresh memory BW1, each dot of the screen is assigned one cell K. Pierick et al 1-1-2-2 ~(~3~ 3 ~ 5 for each primary color. The state of this cell is trans-ferred over a high-speed serial bus -to the image-~orming system of the screen~ Each cell of the refresh memory ;s selected ;ndividually and independerltly from a computer CPU over a parallel bus" said computer being contained in the screen controller or in the refresh-memory module~ The compu~ter generates the respective dot combination in accordance with a code word transferred to ;t over a control l;ne SL, wh;ch ;s operated in a fail-safe mode, e~g.~ a two-channel mode, from a fa;l-safe control computer (SR),consist;ng in th;s embod;ment of two separate computers R1, R2 operat;ng in a parallel mode wh;ch compare the results created by them~
Depend;ng on the code word appl;ed~ the computer in the screen controller w;thdraws the informat;on assigned to the code word from a read-only memory or performs given program steps which resuLt in the, e.g~, vector-graphic creation of the p;cture data assoc;ated w;th the picture element determined by the code word~
S;multaneously with the transFer of these picture data into -the f;rst refresh memory BW1, these data are trans-ferred into a second refresh memory B~2 which is not followed by a screen. There they remain stored as ~ong as the associated p;cture element ;s visible on the screena During the time that the picture data are re-peatedly read From the first refresh memory and dis-played on the screen, the picture data stored in the second K. Pierick et al 1-1-2-2 36~3 refresh memory are read back into the computer CPU and fed to a check-code generator P for generating a characterist;c check code. This check-code generator, l;ke in the prior art, may include a -feedback register, but it may also include a subroutine of the computer CPU contalned in the screen controller.
The check code is transferred over the control line SL
to the check computer SR and compared by the latter with a reference check code stored for each code word from the screen controller ;n a memory (not shown) of the control computer.
Instead of storing the picture data in a second refresh memory, the picture data can be stored in a port;on of the first refresh memory which is not used for the screen display. The second refresh memory BW2 can then be dispensed with. If two or more screens are to be supplied with picture data from the screen controller, further refresh memories may be pro~ided. One refresh memory may then be used by all screens as the second refresh memory.
If the computer of the screen controller is programmed so as to be able to load the second refresh memory BW2 with picture data independently of the f;rst refresh memory BW1, which supplies the screenj it ;s possible to additionally check the creation of those picture data whirh are associated with a picture element that must not appear on the screen at that time~ Thus, the creation of picture elements to be displayed uery K. Pierick et al 1-1-2-2 36~)~3 rareLy, such as the symbol for a switch-trail;ng message in a railway si0naLling system, can be checked without a service interruption~ The picture data created only for checkiny purposes are generated if the code word outputted by the control computer in-cludes a spec;al check flag. The picture data created in response to such a code word are also marked as check data and, because of this marking, can only be entered into the second refresh memory~ so that any unintentional display of these check data on the screen is excluded.
K~ Pierick et al 1-1-2-2
Claims (4)
1. Apparatus for the fail-safe display of an indicating diagram consisting of a plurality of predetermined pic-ture elements on a screen, comprising a fail-safe con-trol computer which outputs code words assigned to individual picture elements to a screen controller which converts the code words into picture data capable of being displayed on the screen and stores them in a re-fresh memory preceding the screen, and a check-code generator which derives a check code from the picture data outputted by the screen controller and feeds said check code to a comparator which compares it with a reference check code outputted by the control computer and stored in a reference-code memory, and initiates an error indication if the check code does not match the reference check code, c h a ra c t e r i z e d i n that the refresh memory (BW1) is a memory having individually selectable dot cells, that a second, like memory (BW2) is provided which is not followed by a screen and to which the pic-ture data created by the screen controller (BA) are fed in parallel, and that the screen controller reads said picture data out of the second memory and feeds it ZPL/S-P/Ke/Lo 20 January, 1991 K. Pierick et al 1-1-2-2 to the check-code generator (P) for generating the check code.
2. Apparatus as claimed in claim 1, characterized in that the second memory (BW2) is a portion of the refresh memory (BW1) which is not needed for the screen display.
3. Apparatus as claimed in claim 1 or 2, characterized in that the second memory (BW2) can be loaded with picture data independently of the refresh memory (BW1) or the portion of the refresh memory which is not needed for the screen display.
4. Apparatus as claimed in any one of the preceding claims, characterized in that the function of the com-parator is performed by the control computer (SR), and that to this end, the check code is fed to the control computer in a fail-safe mode.
K. Pierick et al 1-1-2-2
K. Pierick et al 1-1-2-2
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP4005393.8 | 1990-02-21 | ||
| DE4005393A DE4005393A1 (en) | 1990-02-21 | 1990-02-21 | DEVICE FOR SIGNAL-RELIABLE REPRESENTATION OF A REPORTING IMAGE |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2036013A1 true CA2036013A1 (en) | 1991-08-22 |
Family
ID=6400624
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002036013A Abandoned CA2036013A1 (en) | 1990-02-21 | 1991-02-08 | Apparatus for the fail-safe display of an indicating diagram |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0443377B1 (en) |
| AT (1) | ATE139353T1 (en) |
| CA (1) | CA2036013A1 (en) |
| DE (2) | DE4005393A1 (en) |
| ES (1) | ES2090152T3 (en) |
Families Citing this family (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CH683953A5 (en) * | 1992-04-30 | 1994-06-15 | Siemens Integra Verkehrstechni | Procedure to improve the signal-related safety of the user interface of a data processing system. |
| DE4332143A1 (en) * | 1993-09-17 | 1995-03-23 | Siemens Ag | Process for operating a visual display device and devices for carrying out the process |
| FR2729482A1 (en) * | 1995-01-17 | 1996-07-19 | Alsthom Cge Alcatel | METHOD FOR SECURING THE DISPLAY, ON A SCREEN, OF SYNOPTICS REFLECTING THE STATE OF A SYSTEM |
| DE19703574A1 (en) * | 1997-01-31 | 1998-08-06 | Alsthom Cge Alcatel | Process for the safe display of an image on a monitor |
| DE19830926A1 (en) * | 1998-07-10 | 2000-01-13 | Alcatel Sa | Process for the safe display of the status of a signaling system |
| FR2792429B1 (en) * | 1999-04-19 | 2001-07-13 | Cit Alcatel | METHOD FOR DISPLAYING GRAPHICS ON A VISUALIZATION MEANS |
| ITSV20020018A1 (en) * | 2002-05-03 | 2003-11-03 | Alstom Transp Spa | DEVICE FOR PROCESSING OR COMMAND OPERATING IN INTRINSICALLY SAFE |
| US20050276514A1 (en) * | 2004-06-14 | 2005-12-15 | Fisher Paul A | Image monitoring method and system |
| NO2244188T3 (en) | 2009-04-25 | 2018-05-19 | ||
| DE102011005188A1 (en) | 2011-03-07 | 2012-09-13 | Siemens Aktiengesellschaft | Railway Control System |
| DE102012221714A1 (en) * | 2012-11-28 | 2014-05-28 | Siemens Aktiengesellschaft | Method for fault disclosure in interlocking computer system with control channel, involves comparing pixel data of display with process data of process image of state information of reference system for display-protection |
| EP3549842B9 (en) | 2018-04-06 | 2022-09-28 | Thales Management & Services Deutschland GmbH | Train traffic control system and method for safe displaying a state indication of a route and train control system |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3324313A1 (en) * | 1983-07-06 | 1985-01-17 | Standard Elektrik Lorenz Ag, 7000 Stuttgart | Device for the failsafe representation of information on a data display device |
| DE3411015A1 (en) * | 1984-03-24 | 1985-09-26 | Standard Elektrik Lorenz Ag, 7000 Stuttgart | Method and device for the failsafe representation of a mimic diagram on a screen |
| JPS6470848A (en) * | 1987-09-11 | 1989-03-16 | Fujitsu Ltd | Picture display control system |
| GB2215955A (en) * | 1988-03-23 | 1989-09-27 | Benchmark Technologies | Off screen memory |
| DE3810500A1 (en) * | 1988-03-28 | 1989-10-12 | Siemens Ag | Method and arrangement for generating changing pictures on the screen of a visual display unit |
-
1990
- 1990-02-21 DE DE4005393A patent/DE4005393A1/en not_active Withdrawn
-
1991
- 1991-02-08 CA CA002036013A patent/CA2036013A1/en not_active Abandoned
- 1991-02-08 AT AT91101721T patent/ATE139353T1/en not_active IP Right Cessation
- 1991-02-08 DE DE59107909T patent/DE59107909D1/en not_active Expired - Lifetime
- 1991-02-08 EP EP91101721A patent/EP0443377B1/en not_active Expired - Lifetime
- 1991-02-08 ES ES91101721T patent/ES2090152T3/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| ES2090152T3 (en) | 1996-10-16 |
| DE4005393A1 (en) | 1991-08-22 |
| EP0443377A3 (en) | 1992-12-16 |
| EP0443377A2 (en) | 1991-08-28 |
| ATE139353T1 (en) | 1996-06-15 |
| EP0443377B1 (en) | 1996-06-12 |
| DE59107909D1 (en) | 1996-07-18 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |