Embedded Systems Impactsgreenspun.com : LUSENET : TimeBomb 2000 (Y2000) : One Thread |
Ive gotten many calls requesting types and examples of embedded systems and equipment failures. There are numerous notes at vendors web sites on which of their equipment and software is non-Year 2000 compliant, but very little on what such non-compliance could do to your specific application. It is impossible to state with certainty exactly what your problems will be without evaluating your specific system/equipment, but the following list does provide some examples of what impacts have been found and what the consequences of those impacts are. Some of the more interesting ones and my notes are in italics. If anyone would like to contribute to my ever-growing list of impacts, please do so.
1. Application Type: Weighing of finished product.
Description: Apparent failure to recognize leap year. Jumps from 28/2/00-1/3/00
Solution: PROM replacement
Consequences: Possible breach of regulatory requirements. Some versions count year transitions to identify leap years.
2. Application Type: Date coding (ink jet) of finished product
Description: Unit fails to roll coding date forward correctly once code date is in Year 2000 (failure as soon as forward date hits Year 2000)
Solution: Replacement PROM
Consequences: Serious problem if not rectified. Manual date entry possible, but given the number of units this would present major difficulties.
3. Application Type: HVAC - Control of mechanical services and air conditioning equipment.
Description: Controller fails on first power-up after roll over (12/31/99-1/1/00) whether roll over was with power on or off.
Solution: Replacement PROM.
Consequences: Nuisance failure of services to manufacturing plants resulting in significant downtime. Actual date unimportant so a workaround is possible.
4. Application Type: Instruments - Weighing of finished products (multiple weighers on network).
Description: System fails to roll over correctly.
Solution: Software update required
Consequences: Failure to meet regulatory requirements for average weight. This problem could be a significant nuisance as manual operation of these instruments is difficult.
5. Application Type: PLC-based control system
Description: Unit passes all Y2K tests but at transition from 12/31/03 - 1/1/04 reverts to 1/1/00. (Editors note: January 1, 2000 is NOT the only problem date embedded systems have. It will be necessary to check numerous dates depending upon type and functionality of embedded code. )
Solution: Replacement PROM.
Consequences: Failure of unit.
6. Application Type: Card access control system for site and internal departments
Description: System fails at roll over and access is barred.
Solution: Replace.
Consequences: Security system inoperable. Additional manning required.
7. Application Type: SCADA Operator interface and display system
Description: Custom firmware fails roll over test. PC platforms also fail.
Solution: Replace
Consequences: Key manufacturing plant constrained in operation. Most major functions operable albeit at reduced efficiency, but data logging, etc. lost. (Editors note: How long can you operate at a reduced pace and remain in business?)
8. Application Type: SCADA Bought-in graphics/display package.
Description: Core functionality OK, but some optional modules fail roll over test.
Solution: Upgrade or replace.
Consequences: Largely cosmetic (loss of data logging and trending information), but could be more serious in the event of major plant problems and lead to additional downtime. (Editors note: If efficiency is important to you, loss of trend data can lead to cascading losses and eventual failures.)
9. Application Type: DCS Control System controlling smelter plant
Description: Rollover to year 2000 System on reboot reverted to incorrect date
Solution: Replace battery backup
Consequences: Loss/corruption of trend data. (Editors note: If efficiency is important to you, loss of trend data can lead to cascading losses and eventual failures.)
10. Application Type: DCS control system control for petrochemical plant
Description: Online roll over to Year 2000 dates caused failure
Solution: No known workaround. Plant had to be operated from one station until problem could be rectified. Replacement is necessary.
Consequences: Near catastrophic. Limited reliability and operability of plant. Reduced production. (Editors note: You do not need more than one failure to significantly affect a plant. Percentage numbers are meaningless at this level of embedded systems use. Individual items of equipment can bring you down while multiple failures of other items can have very little effect.)
11. Application Type: Car Park Management System
Description: Dates after 12/31/99 not handled correctly
Solution: Replacement of hardware and software
Consequences: Loss of revenue, lack of car parking causing traffic congestion, safety considerations if car park egress not possible or restricted.
12. Application Type: Fire Station Alarm Monitoring System. System provides the fire Department with information regarding the state of alarms of critical systems. Control of lighting and motorized doors is also possible through this system.
Description: Problems were experienced with the Visual Basic platform that the monitoring software runs on. (Editors note: You have to test all layers of potential problems. These embedded systems are simply PCs in different clothes.) The system will have incorrect knowledge of the day of the week post 31/12/99, and will be unable to recognize February 29, 2000.
Solution: 1) Replacement of PC with Y2K compliant version; 2) replacement of Visual Basic platform with Y2K compliant version; 3) installation of operating system necessary for latest version of Visual Basic; 4) amendment of custom code as necessary to run on the new platform. (Editors note: Once you change the platform, language version and/or compiler version, you must check the functionality of the code. Compiler versions especially will mess up functionality.)
Consequences: Incorrect knowledge of the days of the week will lead to incorrect identification of silent and normal hours. Failure to recognize leap day will lead to system crash. Both of the above constitute safety risks. If the operator is not aware of computer errors, incorrect action could be taken by fire department.
13. Application Type: Logging / Monitoring - Measures and records personal external dose information for those working in radioactive areas. Entry/exit records are date/time stamped and are stored in a database.
Description: The real time clock within the PC will not roll over correctly. As a result of this dose records over a given range will total incorrectly and reader and software records will be incorrectly date stamped. The DBU software will roll over to 1900. This will result in the loss of some dose records, making over-exposure of some operators possible. (Editors note: Creation and storage of data is just as important as use.)
Solution: Replace the PC used for the IDR software with a fully Year 2000 compliant version.
Consequences: Incorrect dose records would cause the regulator to take action, possibly closing the facility until it could be proved that corrective actions had been successfully implemented. Possible legal costs and personnel injury damages.
14. Application Type: Train Describer. This system provides information about locations of train services to signalers and other rail staff. The output is used to update a train position model that places each train's unique description (head code) on a schematic representation of the rail network.
Description: The Train Describer computer is non-compliant. The system software clock stores date with a 2-digit year, however, it prints dates with 4-digit years by using the prefix '19' in output to the printer. (Editors note: Just because a printout uses four digit year fields does not mean that your system does.) On start up the system will accept dates in the range 10/10/84 to 31/12/99. Dates outside this range will be rejected as invalid. The system will rollover to '00' if left powered up. However, in the event of a failure it will not be possible to restart the system and enter the correct date after 31/12/99. The day of the week will be incorrectly calculated after the 2000 leap day, so the Describer may refer to the wrong timetable.
Solution: Modifications are possible to make the system compliant. However, it is reasonably old and difficult to maintain, so replacement is preferable.
Consequences: Loss of knowledge of train location, trains running at incorrect times, late or not at all.
15. Application Type: Site-wide building access control and security system consisting of six connected controllers at various site locations controlling a network of card readers and keypads (supported by modems etc), printers and visual display terminals.
Description: The control panel will roll over correctly from 02/28/00 to 02/29/00. However, if 02/29/00 is entered manually, it will default to 02/01/00. (Editors note: Have you checked all possible user inputs to see if they could affect your system?)
Solution: The access control software will be upgraded and the control panels replaced.
Consequences: Nuisance, access to restricted areas may be controlled using a manual, paper-based system. However, this would be expensive and time consuming.
16. Application Type: A robot used to change air filters in a restricted area has a PLC controller. The robot may be used in automatic mode controlled by its PLC. It can also be used in manual mode, but the operator relies on the PLC to receive information from sensors on the robot arm. Completely manual operation is not possible.
Description: PLCs running certain versions of the operating system will fail to roll over into the next century correctly. This will disable the robot. Problems will not be experienced immediately as the robot is not in constant use. (Editors note: Are you sure you have checked and tested ALL of your equipment?) However, failure to correct the problem would seriously impair production. The operator terminal used to program the PLC is non-compliant, as is the programming software. It may be difficult, if not impossible, to roll the PLC system clock back and, if necessary kit changes cannot be made, production will be stopped.
Solution: Complete replacement of the PLC.
Consequences: Production must stop. Unless a solution is found regulatory non-compliance would follow.
17. Application Type: System used for voice and data communications between train drivers and signalers.
Description: Before updating the time, the management processor sets all of its internal registers to zero, and monitors the status of them afterwards. If the status of one or more registers is still zero, this is interpreted as message not received. The processor will await the arrival of a valid signal before updating the time and date. So, effectively, it will cease to function for one year, then resume normal operation on 01/01/01.
Solution: The equipment manufacturer must provide a software upgrade.
Consequences: If information gets out of sequence, chaos will ensue. Train delays will occur, and there will be increased risk of rail accidents. The cost of this could be considerable. There will also be regulatory problems as, in the event of an emergency, logs and sequencing information is needed for post-incidence inquiries.
18. Application Type: Tracking system used on 6 meter and 8 meter satellite dishes. This tracking system is used to position satellite dishes that provide uplinks to communication satellites in geostationary orbit.
Description: The tracking system rolls over into the next century and the data '00' is interpreted as an invalid date. Knowledge of the date is essential to finding the position of the satellites.
Solution: There are three possibilities: 1) Upgrade the tracking system; 2) use alternative transmission means; 3) transmit using smaller satellite dishes on higher power.
Consequences: It will not be possible to broadcast signals. (Editors note: Make sure embedded systems impacts wont impact your expected contingency plan actions.)
19. Application Type: SCADA system that provides an overview of the operation of approximately 250 systems in a manufacturing plant.
Description: The system failed during the power down roll over test. It would not start up again when power was re-applied. The system was restored from backup and the successfully re-initialized.
Solution: The problem was rectified immediately by the vendors. Software modifications were made.
Consequences: If this failure happens on restarting the system after the millennium shutdown, and the system backup is not readily available to restore the system, then this type of problem could result in significant downtime.
20. Application Type: A smart density analyzer uses a radioactive source as part of its measuring process.
Description: The algorithm that compensates for the decay of the radioactive source gives erroneous results on rollover to January 1,2000.
Solution: It was initially thought that the solution would be to recalibrate the instrument on December 31, 1999 (enter a date of January 1, 2000), and then to recalibrate again on January 1, 2000 (enter the date of January 1, 2000 again). Testing discovered that doing two sequential recalibrations also caused major problems. (Editors note: Be sure that your solution does not cause problems. Test your solution before final implementation.) The vendor is now offering users of the system an EPROM upgrade.
Consequences: In an operating process, this would raise alarms and possibly result in a costly process shutdown.
21. Application Type: Multi-site organization has a packet switching mechanism to allow medium speed data communications.
Description: Each communication node in the network has a real time chip in the node firmware. The firmware only 'sees' two digit dates. The system will not function correctly if allowed to roll into the next century. The packet switching management system is a supervisory level system with non-compliant operating system in conjunction with non-compliant application software. (Editors note: This system has all three problems, firmware, operating system and application software. All should be checked for proper functionality.)
Solution: The packet switching device will have its internal clock wound back by 28 years to synchronize days of the week and leap years. The packet switching management system will be completely decommissioned. No fix has been identified for the application system although the operating system could be upgraded.
Consequences: The management system is the key to determining fault location, performance metrics, and event reporting. Without the management system, it will be difficult to manage with faults, and alterations will take longer to deal with, thus impacting network resilience.
22. Application Type: A multi-site utility company has 1.2 million meters (30% electronic and 70% mechanical). A problem arose with the calibration equipment for the electronic meters.
Description: On testing electronic meters and rolling through the post 2000 dates, the calibration equipment 'stuck' at 2010. It was impossible for the user to reset the calibration equipment. The vendor had to be called in. (Editors note: January 1, 2000 is not the only possible problem date. With the lack of a universal format standard, we run risks every year.)
Solution: The vendor reset the calibration equipment and inserted an upgrade patch.
Consequences: This caused a major logistical problem as a backlog of calibration checks built up.
23. Application Type: Fuel Pump
Description: Year does not roll over. Leap years are not recognized.
Solution: Client "working around" fault. Owner has to manually correct date on each January 1st.
Consequences: Inability to monitor fuel dispensation.
24. Application Type: HVAC - Air Conditioning/Heating Controls
Description: Loss of control of HVAC system. Critical date 01/01/2000.
Solution: Upgrade software. Manufacturer supplying free upgrade.
Consequences: Potentially catastrophic.
25. Application Type: Fire alarm control panel - sounds alarm.
Description: There would be a fire alarm malfunction on rollover - alarm raised.
Solution: Software upgrade.
Consequences: Would lead to building being evacuated.
26. Application Type: Water leak detection.
Description: Non-reporting of leaks/fire alarms. This type of problem could be either no alarm, false alarms, or both. The critical date for this specific system was 01/01/2000.
Solution: Upgrade microprocessor.
Consequences: Non- reporting of leaks could cause major damage with long down times. False alarms would cause systems (e.g.. air conditioning) to be closed down.
27. Application Type: Building Energy Management System
Description: The system will operate correctly through the millennium rollover if the system remains powered. If the system is powered down, however, the date will revert to XX/XX/1900. (Editors note: If you can absolutely believe that your system will never be powered down, then you dont have to fix this type of problem.)
Solution: Upgrade/ replace equipment.
Consequences: Potential failure of air conditioning/ heating system, security systems etc.
28. Application Type: Fire Alarm Panel.
Description: System crashes on rollover, but can be reset in year 2000. However, it doesn't recognize leap years. (Editors note: You should do a leap day test for 2000, 2001 and 2004.) The critical date for this specific system is 01/01/2000.
Solution: Replace equipment.
Consequences: Building is left unprotected if system is not reset immediately after rollover.
29. Application Type: SCADA - Supervisory control & archive data for production process.
Description: Loss of communications to discrete control functions and failure of archiving process data due to 2 digit date field use.
Solution: Fix installed by manufacturer
Consequences: Loss of heating models for process. Manufacturing an unusable product. Loss of process data for quality control and QA.
30. Application Type: SCADA - Monitoring of high frequency welding equipment
Description: All data logging after January 1, 2000, would be erased as old data. (Editors note: Have you checked to see if you could properly write data or files during your Y2K tests?).
Solution: A software patch is available and will be installed by original supplier of equipment. This original supplier had been unaware of the problem and consequently will need to fix several hundred similar systems worldwide
Consequences: Loss of historical trending data and traceability for QA.
31. Application Type: Level and flow monitoring of waste acid treatment plant Instrument
Description: Problem experienced with some versions of firmware. If the unit rolls over any year (its not a Y2K specific problem) with the power supply off, then on power up, the display is blank and the keyboard locked so that the device will not operate.
Solution: A known compliant version of the firmware has been installed. Long term, the unit will be replaced.
Consequences: Inability to treat acid, resulting in shutdown of plant.
32. Application Type: DCS - Wire Loom Testers. This is a stand-alone system, which is not connected to any computer network. It performs electrical continuity tests on aircraft wiring looms.
Description: On rollover, the PC attached rolls to 00, but the certificates printed out for the customer show the date as being in the year 100.
Solution: The PC and its software are to be replaced with a compliant version.
Consequences: The system is unable to produce valid certificates for the customer. The customer will reject invalid certificates as they form part of the contract for the aircraft. Consequently, aircraft delivery will be stopped. (Editors note: What are your contractual requirements for documentation and have you included them in your testing?)
33. Application Type: Logging / Monitoring - This system is found in the automotive industry and is concerned with the "just-in-time" manufacture of airbags. The assembly line is made up of a number of stations. The action carried out at each station is controlled by a dedicated PLC that operates independently of all other PLCs. The whole line is controlled via a main line computer which carries detailed information about the product being assembled and the route map through the manufacturing line, and serves as the link between the assembly line and a network based database.
Description: The reference date is used for comparison against the manufacturing date of components that are included in the assembly. Tests revealed that the PLC performing this comparison performed correctly. Further tests revealed that another part of the assembly line suffered a different date-related problem that involved the current production date. The problem was found to be the result of converting the year data (100) into two digits (YY) resulting in the printed label containing :0 as representation of the year 2000. It was found that products carrying labels with year :0 are rejected as a result of invalid year code (Editors note: All systems should have end-to-end tests carried out. Definition of a system should include ALL aspects of manufacturing, packaging, shipping, distribution, etc.) .
Solution: The date handling routine in the label printing software was modified to represent the year 2000 as 00. Tests were carried out to verify this and found that a fault was again registered. This was traced to the PLC code that compared the year code on the label (00) to the year code in the MDT (100). Therefore a further modification was carried out on the data received from the MDT to represent the year 2000 as 00.
Consequences: Loss of production on three assembly lines.
34. Application Type: CNC Milling Machine. The system is used to manufacture aircraft parts and is controlled by PLCs.
Description: At the 31/12/1999-1/1/2000 transition, the PLCs BIOS resets from 31/12/99 to 4/1/1980. Numerical Control (NC) program data with the current date (1/1/2000) is then downloaded from the DNC network. There will now be a date conflict between the downloaded NC data and the internal date (Editors note: This is why you should accomplish end-to-end tests on all systems possible internal date (really format) conflicts.).
Solution: Upgrade of operating system in 3 stages.
Consequences: Confusion over NC files that are downloaded over the site network due to date discrepancies. There are three of these machines dedicated to the same task, all are identical and therefore consequence of failure is increased threefold. As far as known, these are the only machines available to manufacture the aircraft parts to the proven method at this site.
35. Application Type: HVAC - The system comprises: (1) a centralized PC (with the appropriate software) that monitors and controls the operating parameters of both a boiler management system and microprocessor-based out stations; (2) local area network that connects the outstations and boiler systems to the PC via networked hubs; [3] portable hand-held computers that are used in the programming of the outstations with, for example, local operating characteristics; (4) air-conditioning units (ACU).
Description: While conducting the tests it was found that when power was removed from the outstations and subsequently re-applied (Editors note: Do your tests include a power-on and power-off rollover?), the outstations failed to recognize leap years. As a result of these omissions the history logs held in the central PC became corrupted. For example, if the PC was expecting data for the 29th February 2000 it received data (from the outstations) for what the outstations believed to be the 1st March 2000 (since the 29th February had been "lost").
Solution: There are two possible solutions (excluding the "do nothing" option): 1) Upgrade the firmware versions of the out-stations 2) Replace the system software.
Consequences: The system would activate (or deactivate) at various times during the year.
36. Application Type: Instrument - An "electrical continuity tester" (ECT). It is a standalone instrument and is made of: 1) a master switching console (MSC) that connects the wiring loom under test to the ECT by means of a 100-way cable; 2) a PC is connected to the ECT by means of an RS232 link. This computer contains all the programs required to automate the operation the ECT and record the results of the tests; 3) the ECT is connected to an electricity supply and contains banks of manually operated make or break switches.
Description: The problem that occurred is as follows: On December 30, 1999, it would not have been possible to set the system's operation for January 1, 2000. The PC would have interpreted the year as 1900. That means that the license would become invalid, which in turn means that the system would refuse to operate (Editors note: Have you investigated all possible license ramifications?). Given that the system would fail to operate, it is not possible to identify any further effects of non-compliance.
Solution: Replacement
Consequences: Given that the license would prevent the system from operating, the product being manufactured could not be tested and therefore could not be sold. In the short term the credibility of the business would suffer. In the medium term customers may impose (financial) penalties because the product had not been delivered on time. In the longer term the business may cease operating
-- G Bailey (glbailey1@excite.com), November 22, 1999
As a little added 'spice', consider the fact that all of those 'Prom replacement' fixes refer, not just to the Prom, which is merely Programmable Read Only Memory, but the *code* that is contained in them. So this isn't merely a case of changing a chip, but first writing a new (or correcting the old, assuming that this is possible, i.e., that the source code still exists, is in a form that can be worked with, that a compiler version compatible with it exists, that there is a development platform on which this compiler version can be run, that the linker and loader versions exist and are compatible with the compiler and the platform, and that there exists a pin compatible replacement for the original prom chip.Now consider that there are many places where the official policy is to 'Fix-on-Failure'.
-- just another (another@engineer.com), November 22, 1999.
Embedded Systems Impacts
October 6, 1999
-- G Bailey (glbailey1@excite.com), November 22, 1999.
I don't think I'm going to read your posts anymore. I never see any good news!
-- Laura (Ladylogic@aol.com), November 22, 1999.
G Bailey, Can you please provide us with the source of these reports, and the manufacturer/model number of the equipment so that we can verify this data? I recognize some of the reports, some are quite credible, others are not. Again, it looks like facts mixed with many outright false claims and exagerations - like a Y2K services companies PR hype, like the Y2K movie...I'm not going to waste much time on this, but here are two of the many examples of some of your erroneous "failure reports":
"16. Application Type: A robot used to change air filters in a restricted area has a PLC controller. The robot may be used in automatic mode controlled by its PLC. It can also be used in manual mode, but the operator relies on the PLC to receive information from sensors on the robot arm. Completely manual operation is not possible.
Description: PLCs running certain versions of the operating system will fail to roll over into the next century correctly. This will disable the robot. Problems will not be experienced immediately as the robot is not in constant use. (Editors note: Are you sure you have checked and tested ALL of your equipment?) However, failure to correct the problem would seriously impair production. The operator terminal used to program the PLC is non-compliant, as is the programming software. It may be difficult, if not impossible, to roll the PLC system clock back and, if necessary kit changes cannot be made, production will be stopped.
Solution: Complete replacement of the PLC."
Well, this is the first claim I have heard from anyone of having to replace an entire PLC, and I frankly don't believe it. Please provide the manufacturer and model number. The write up doesn't make a lot of sense - I've worked with PLCs for years. It "may be difficult, if not impossible, to roll the PLC system clock back". MAY BE? They don't even know??? This is utter nonsense. If this PLC has a date function, it almost certainly has a real time clock, and the program will let you set the date - I have never heard of a PLC that wouldn't let you set the date back. Additionally, it is rare to use a PLCs DATE information in the program control, and I would like to see evidence that this one does as well. AND, I have yet to see a PLC just "stop" due to a y2k bug, so the operator should be able to get his data. Manufacturer and model number please, I wan't to check this one out for myself. This report looks like it came straight from Bobs TV repair and Y2K emporium....
"36. Application Type: Instrument - An "electrical continuity tester" (ECT). It is a standalone instrument and is made of: 1) a master switching console (MSC) that connects the wiring loom under test to the ECT by means of a 100-way cable; 2) a PC is connected to the ECT by means of an RS232 link. This computer contains all the programs required to automate the operation the ECT and record the results of the tests; 3) the ECT is connected to an electricity supply and contains banks of manually operated make or break switches.
Description: The problem that occurred is as follows: On December 30, 1999, it would not have been possible to set the system's operation for January 1, 2000. The PC would have interpreted the year as 1900. That means that the license would become invalid, which in turn means that the system would refuse to operate (Editors note: Have you investigated all possible license ramifications?). Given that the system would fail to operate, it is not possible to identify any further effects of non-compliance.
Solution: Replacement"
This one was hilarious, I love it! "The PC would have interpreted the year as 1900. That means that the license would become invalid, which in turn means that the system would refuse to operate." The PCs LICENSE would be invalid??? And therefore the PC would "refuse" to operate? Good one, lol.
Regards,
-- FactFinder (FactFinder@bzn.com), November 22, 1999.
From justanother: "As a little added 'spice', consider the fact that all of those 'Prom replacement' fixes refer, not just to the Prom, which is merely Programmable Read Only Memory, but the *code* that is contained in them. So this isn't merely a case of changing a chip, but first writing a new (or correcting the old, assuming that this is possible, i.e., that the source code still exists, is in a form that can be worked with, that a compiler version compatible with it exists, that there is a development platform on which this compiler version can be run, that the linker and loader versions exist and are compatible with the compiler and the platform, and that there exists a pin compatible replacement for the original prom chip."Justanother, I have worked on several y2k projects, it IS usually just a matter of replacing the PROM chip- and the vendors have already DONE the programming for equipment they support. In those cases where the product is no longer supported, the devices themselves can be replaced with newer devices. I have yet to hear from other engineers about "pin compatibility" problems, most PROMs are in standard packages.
Now consider that there are many places where the official policy is to 'Fix-on-Failure'.
Please provide documented examples with links to companies OR countries that have posted this "official policy". I want to read these official policies.
Regards,
-- FactFinder (FactFinder@bzn.com), November 22, 1999.
FactFinder --First, if you haven't ever had 'pin compatibility' problems with IC's then I would suggest you quit posting here and get your diaper changed. Because you have to be about 6 months out of college. If that. This was a *COMMON* problem in the 80's. That you have never experienced it costs you a great deal of credibility, with me at least.
This second one is a *little bit* harder. Think, now. If someplace, like say, Chicago's Water Department, (to name one where they are still arguing over spending the money to upgrade the system to something that might actually continue working after the rollover, as the person in charge bid the contracts without letting the County Board President, John Stroger, get enough graft or enough relatives hired on), doesn't have a plan for doing the fixes *BEFORE* Jan. 1, 2000, then I would call that an "official" 'Fix-on-Failure' by default. Wouldn't you.
Oh, that doesn't meet your standards? How 'bout this one? Company I work for, (and no, I am not going to name it. It may not be there after the 1st, but I'll stay with it to the bitter end, and will be there until we go down swinging. Won't get myself fired *and* tied up in lawsuits this close to the rollover.) This company has 'talked the talk' *AND* walked the walk. It has been through 2 (that's two) rounds of inventory, assessment, remediation, test, and evaluation. TWO! And we have probably got as many problems as we did when we started. And the 'unofficial' (announced to those who have to do the work, not to the general public) "Official" policy is now 'Fix-on-Failure'. Wait and see what it is that goes belly-up and see if we can work around it, fix it, replace it or what.
Still not satisfied? Okay, at last count there were about 850,000 SME's that were doing *NOTHING*. That surely ought to count as 'Fix-on-Failure'.
Even with all of this staring you in the face, I am guessing that you don't hear because you don't *want* to hear. This isn't a debating society. But all you folks want to do at times is argue over 'Well that's not how PLC's work'. Well, sometimes it is. That may be how they were programmed. I haven't *ever* worked with 'PLC's', as I have pointed a several times, but I am given to understand that they are just 'central system controllers in a fancy box'. And I *DO* understand how system controllers work. Both microprocessors and microcontrollers. Because I have written several dozen proprietary, stand-alone, and custom control applications for embedded microprocessors and microcontrollers.
Those who say that no PLC (read system controller) would just stop betray an absolute *IGNORANCE* of one of the first principles of control work. IF THE MACHINE HAS AN UNDEFINED CONDITION, *STOP PROCESSING AND FAIL SAFE*! You *DO NOT* run equipment which you don't know what it is doing!!!
Gonna keep running that liquefied helium right down that there pipe and I don't *care* what the stupid flow meter says. (There is a hole in the pipe and you are dumping it out on the floor, but *YOU* don't care, you ain't sitting there up to your butt in 2 degree absolute liquid, you're in your nice warm cubicle.
If this is your level of understanding of this sort of task, then perhaps you had better knock off the 'expert' opinions.
-- just another (another@engineer.com), November 22, 1999.
Reply to "just another engineer"
-- FactFinder (FactFinder@bzn.com), December 05, 1999.
Woops, wrong thread, reply is here: Rely to "just another engineer" http://www.greenspun.com/bboard/q-and-a-fetch-msg.tcl?msg_id=001w15
-- FactFinder (FactFinder@bzn.com), December 05, 1999.