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Ask Slashdot: Supporting "Antique" Software?
First time accepted submitter wolfguru writes "As the IT Manager for a large printing firm, I often have to provide hardware to support older software which is used to configure and maintain existing systems, some of which are nearly 20 years old. Much of the software uses RS-232 serial communications to connect to the PLC devices and is often 16 bit versions. Newer systems from the PLC manufacturers supports some of the equipment, but many of the older PLC consoles are essentially unreachable without the serial communications. For any of you faced with similar challenges in keeping a manufacturing environment maintenance department working; what do you use to support them and where do you find equipment that will run the older systems that are sometimes the only means of supporting these types of devices?"
The DOSBox forums are fled by incompetent IT pros that demand support for their old versions of dBase. It's rather depressing.
Fortunately RS232 is still well supported via PCI-e cards and USB, so you can just run the old system in a virtual machine on modern hardware to avoid many of the problems associated with maintaining old gear.
My only other advice is to never underestimate the costs, especially when talking to your boss. He/she will want guarantees that everything runs smoothly all the time, which realistically you can't provide without plenty of redundancy and extensive testing. Be clear that old hardware is hard to maintain and repair, and not trivial to replace.
const int one = 65536; (Silvermoon, Texture.cs)
SJW, n: "Someone I don't like, and by the way I'm a fuckwit" - AC
It could be ladder logic and plugboards.
http://www.digi.com/products/serialservers/
They are a god send. For software I use RSlinx Gateway which is for Allen-Bradley PLC's, but has many different driver solutions. Also it will allow you to bridge network connections if your running DH 485/RS 232/DF1/ DH/DH+/Ethernet. Gateway is expensive though there might be a more cost effective solution.
It seems that pretty much every datacenter needs a bunch of these: http://www.tripplite.com/en/products/model.cfm?txtSeriesID=849&txtModelID=3914
They work well, though I'm not sure about software, as it was suggested previously, a virtual machine sounds like it should work for what you need.
Sig missing. Reward.
The only issue with your old software will be to make sure it is Y2K compliant, apart from that, it'll keep going forever as long as the surrounding hardware holds out.
Oh, wait....
At work we use Industrial PCs for work with PLCs. You can still buy PC with an ISA slot, and most of industrial PCs have good old serial port. Just contact any competent supplied of industrial automation equipment.
One of manufacturers is Advantech. Have a look at their UNO line of "brick" computers. Plenty of industrial RS232 and RS485 ports even in the most basic models. Computers are fanless and built to last. Unfortunatelly, those machines are bloody expensive.
If you look really hard, you can even find new 486 machines. Those are even more expensive than Advantech bricks I wrote about, but there are still people that need those computers, so there are companies able to provide them at a cost.
The strategy should include a short time support strategy for old hardware. You can run 20 year old software on today's PCs either directly or in a virtual machine. However, you might have problems, because they are too fast. This short term support must be supplemented by a migration strategy for the old PLCs. I know that is hard, have worked in a project using PLCs in railway control systems, which have to run for 20 or more years before they are replaced again. Therefore, you need also a strategy how to replace the replacement in the future.
One important tool to do this, is detailed documentation of protocols (including timings) and semantics of the software.
At a company I used to work for we found that EBay was a great place to buy old equipment we required for our outdated, but still needed, systems (mostly to connect to scales and such). You do need to use a lot of caution when buying there since the quality of the equipment and the quality of the sellers vary a lot. There are also some sellers who have separate online stores where they feature a wider variety of items in order to avoid fees. You may also find someone who sells online also has a physical store location in your area. Visiting a tech graveyard store is a fun way to blow an afternoon. I do agree though with what AmiMoJo said, virtual machines and cost/benefit analysis is going to be better in the long run than trying to keep that IBM AT running.
Never - ever - upgrade.
A few posts ago I wrote about Industrial PCs.
If you need just a serial port, and not complete PC running old software that needs to access serial port directly, there are boxes from Moxa that let you connect dozens of serial ports to one PC.
16 bit software. What OS? Windows 3.1? 2.11? OS/2? DOS? Xenix? Beside the RS-232 problem, finding new hardware for these OS can get difficult. As others stated, you can use VMs to run, but it would help us answer the question if you list the OS. Just finding old OSs can be quite difficult. (legally)
Hi Timothy,
Unfortunately, you didn't provide a lot of information in your post as to what the problems are.
As people have pointed out, there are a ton of USB to Serial solutions out there so having the modern hardware with the ability to communicate over RS-232 is generally not a problem (although, depending on the connections used, you might want to invest in a RS-232 breakout box and read up on RS-232 handshaking as many of the older devices do use hardware handshaking). I have a few hand wired 9 pin to 25 pin connectors with the CTS-RTS and DSR-DTR pins shorted together as they can simplify your life immeasurably.
In my experience, the biggest problem is retaining floppies & CDs with the original software on them (assuming that the developers are no longer supporting the product/are out of business). If the company is still in business, usually they're pretty good at providing updated software for their products. If they're not in business, then look to see if they were bought out by anybody. Chances are you'll find that the purchaser is still supporting the product, although it may be under another name.
Personally, the biggest issue that I see when I have encountered this type of situation is that the original programs are on floppies. If this is the case, you will need to find somebody with a Windows/95 machine that they're keeping together with spit, bailing wire, gaffer's tape and good intentions - you should be able to copy the program onto a USB key and then burn it on a CD/DVD for more permanent storage.
Once you have the program in a media that you can work with, you may have problems with the installation. You will probably have to create a virtual machine on your PC AND there may be 16 bit programs that you have to convert to 32 bit - here's a great resource that's saved me a couple of times: http://www.reactos.org/forum/viewtopic.php?f=22&t=10988
Finally, Google is your friend. Chances are the answers are out there for your particular equipment.
Good luck!
myke
Mimetics Inc. Twitter
But dos and older windows 9X apps / os may not like USB to RS232 and or pci / pci-e based RS232 ports. Also VM pass though may not work 100%.
You can try running free dos / MS-DOS 7.x or 8 on newer hardware but usb may not work as well.
On a modern OS, such as Windows or Linux (preferable), you can use a virtual machine to run older DOS and such operating systems, passing the RS-232 ports of the host though to the virtual machine. Works great for me, and I use that for dealing with similar embedded systems all the time. FWIW, my preferred host OS is a clone of Red Hat Enterprise Linux (RHEL) 6, Scientific Linux (SL). CentOS is another such clone, and widely used in industry. I use SL because I personally know the maintainers of SL at Fermi National Laboratory in Illinois (my wife is a staff scientist/physicist there), so if I have an issue, I can contact them directly. My preferred virtual machine manager tool is currently VirtualBox (open source, from Oracle/Sun), but KVM will also work very well for this. That said, I prefer the GUI and configuration tools provided by VirtualBox.
Sometimes, real fast is almost as good as real-time.
...we run two pick and place machine which run on CP/M daily. Replaced floppy disk (5") with emulator which runs on sd cards and everything works fine.
So, 232 and Windows is a child play :)
All about risks, not just the fact the device is RS-232 only, but can the manufacturer support the equipment and if it fails whats the cost to the business while the machine is down.
Sure we can all get 486's with ISA cards if the device needs connectivity to the outside world, but the device of that is a business risk and needs Mgmt to be aware of the issue.
I've had a parts carousel system go down for weeks while we replace gearboxes, made worse by a switch from AC to DC by the manufacturer. Costs to the business were huge and all production was slowed down. Mgmt were informed of the risks but wouldnt spend any money till if broke.
Basically you're looking at a CYA situation, make sure mgmt are informed in writing (email etc) of the issues around the machines and what costs there are vs getting in new machines and added benefits of new machines
Ethernet and USB to RS-232 are great solutions, but sometimes software is written a little too specific to HW, like CPU clock speeds, system IO chips, etc., and it just won't run in newer OSes and virtualized environments. For that reason I've kept a few older motherboards and systems and I've had to run them from time to time- ISA slots, 5.25" floppies, even 3.25" floppies are rare for me these days but once in a while, needed. About a year ago a guy paid me around $200 to recover lots of files from some XT and AT class hard disks, and I was able to do it (fairly easily).
Everyone has "upgrade fever" but I don't necessarily recommend it. Often the 20 year old software is well written and works 100% in its correct environment.
A good friend of mine works at a company with just this problem. They have a very expensive CNC machine. The software is very hardware dependent- needs to see old AT architecture stuff, the original 5.25" floppy (software key), CPU clock dependent timing loops, etc. The whole machine was wearing out and needed so much overhaul, all new bearings, slides worn, etc., they finally scrapped it, but replacement cost hundreds of thousands. But during it's 25 year lifetime they kept some older PC hardware around for spares and kept it running.
It might be more cost-effective and time-efficient to find some older stuff on ebay. Maybe I should rent out my systems / services!
Here are some observations about why the problem isn't as difficult as you are making it out to be.
First and foremost, for older PLC hardware, the PLC hardware was considered to be the valuable part, and the software/drivers were considered to be overhead that they had to have to sell the hardware. So most of the serial protocols for these things were well documented in order to reduce support costs. In general there was either reluctant free support for their software/drivers, or you paid a fee per incident. If support contracts were an option ... you are unlikely to have kept the payments up this long. So you will likely be writing some code, but you will likely have documentation with which to do it.
Second, the FTDI drivers are crap. They leak kernel memory in Linux when you unplug them while the device associated with them is open. They also do this in the Windows Drivers, and because Mac OS X is religious about its encapsulation model in IOKit, unplugging them in Mac OS X while the device is open generally leads to a kernel panic. Almost all the USB-to-RS232C/RS422 adapters use chips sourced from FTDI, or use clones of the FTDI chips so they don't have to actually write their own drivers. Rampant code copying between vendors is my suspected reason that most of these vendors refuse to document their hardware well enough that an Open Source driver without the bugs could be written. You are unlikely to be happy with USB fobs.
Third, 9 pin RS232C is frequently not enough for a lot of older devices. The RS232C specification allows external clocking of the signal, but these pins are not present on the 9 pin connectors, only on the 25 pin. Additionally, there is out of band signaling that is sometimes used on other RS232C pins that aren't as frequently used that can be necessary. As you are with a printing firm, if what we are talking about here is an old Linotype or similar machine, you are likely to be SOL without full 25 pin RS232C. You should be happy that it isn't an 8 pin DIN cable from an old Mac, since at least you get the RI pin on the 9 pin connector.
Fourth, terminal servers often have these issues, in spades. There are a number of terminal servers where, if you have a blocking outstanding read on the serial port, outgoing writes are blocked until the read completes or times out. They basically expect that you will poll, or that all your communications over the serial port will be synchronous (i.e. you will not end up with output to your Wyse-50 until after you have input something). I can name a number of vendors with 8-port serial cards that have this issue. On the plus side, it's a driver design bug, so if you are swilling to use your own driver, or are willing to go Open Source OS, this is typically not a problem, but you will end up screwed by Windows and Mac OS X -- but a Mac OS X subclass of the broken driver is easier than an entirely new driver written in windows. Computone 8 port cards used to have this problem a lot.
Fifth, and finally, with USB dongles, it's frequent that the modem control signals are borked up. What I mean by this is that until the pseudo tty USB driver on the host side of things is opened, then the pins on the RS232C side of the adapter are floating in an indeterminate state which depends on the USB fob firmware, and is frequently not where you would want e.g. DTR or CTS/RTS or other signals hanging out for an idle serial port. This can make older equipment Do Things(tm), and the oly real remedy is to get the port open, set the signals right, and THEN plug in the serial cable. Generally, this means that you get to have two sets of signal state for setup, in addition, since the line buffers in some of the older devices are not optoisolated, and on those which are, the optoisolation can blow if you immediately apply voltage before ground, etc.. If you think talking to an old PLC is hard, try replacing an ancient Zilog UART on the damn thing.
When you buy a rack mounted unit that does this, it's sometimes called a terminal server. You can provide network to serial access, enable unique passwords on each device and create access lists. When I managed customer equipment, I used to require a DECserver and modem/phone line for last ditch access. In this case, I had firewall, switch, router and console access. Much of this kit is can be found used or see Vnetek. I understand Cisco also makes comparable product. You can pair this with virtual comm port driver, letting you drive these units from a central location.
Answer number 2, you need to put a business risk into supporting antique systems. Cost of replacement, downtime to find part vs lost business. Consider stocking in house pre staged replacement systems.
Just make sure you get one supporting the flow control lines, which most cheapo adapters don't. Most industrial equipment i've worked with wont communicate without those.
Am I the only one laughing at the thought something from the early 90s is now considered antique?
A business critical piece of hardware that needed a custom 8 bit ISA card and Win3.11 to control it. Made sure I had multiple good images of the hard drive because the original floppies were lost. I was burning through old PCs that I kept in storage but found a supplier of 486 computers with ISA slots, so I bought two that I kept in a ready to go state. Thankfully that one custom card was rock solid.
Eventually (last year) the 25 year old machine broke and the company had to pony up the $50,000.00 for a new one which is also much more functional.
We also use lots of RS232. PCI cards from Comtrol have been the most reliable for us.
There are lots of USB-Serial cables, most suck. I only buy from FTDI.
You don't need Win95 to read floppies; USB floppy drives work fine. The real problem is that old floppies are almost guaranteed to be unreadable. As soon as you can copy all your floppies onto cd-rom. I use linux to make floppy images "dd if=/dev/fd0 of=floppy.img". Then they can be mounted, read, stored on cd-rom, used to make new floppies, etc.
RS232 to Ethernet devices have a big security problem - they can expose your RS-232 device directly to the Internet. Many RS232 to Ethernet devices will talk to anything that tries to talk to them. Some have built-in minimal web servers for configuration, and those make it easy for attackers to find the device.
Industrial automation people try to have isolated Ethernets for these devices. But then something comes along that needs to be on the isolated net and also needs to talk to something in the outside world. Then someone reconfigures the isolated net to connect to the outside world. Everything still works fine, until somebody breaks in.
This used to be more of a theoretical attack, but there are now search systems out there finding and cataloging control devices reachable on the Internet.
Virtual machines would provide the bridge you need to consolidate the processing power on the newer machines with antiquity. You can even network a DOS VM. I love the old stuff, making what was.....work.
100% of RS232/RS485 to ethernet adaptors I have worked with have had at minimum IP level filtering. Trivial to defeat, I know, but most sit on networks with no direct connection to the internet. And honestly if you've got a hack on your subnet you have bigger problems than the fact that he can access your unknown (to him) PLC. Like the fact that he can own your SCADA and break things without having to understand ladder logic in the PLC.... Worry about your SCADA first, and your conversion devices second....
I have determined that my sig is indeterminate.
Is see if the PLC manufacturer supports newer hardware/software. I went through this in a few places. Ancient systems in place to do a specific function.
But where I could I replaced them with more modern hardware and software. Sometimes I'd have to write the software myself but it got done.
What about using a terminal server for RS232 stuff? There are plenty of them out there that are designed to give you a console connection to network gear. Seems like you might be able to hack something like this to make it work. Essentially you would load a driver on a PC that makes it think the serial port on the terminal server is a local RS232 port.
I don't understand the question. Why is running hardware via serial ports a problem? Serial ports have been included on almost every PC made for the last 30 years. I have plenty of serial port based hardware. You plug it in. There are literally billions of computers on the planet with serial ports.
I don't respond to AC's.
I had to support a manufacturing company 15 years ago that was using (at the time) 15-20 year old gear. I did it by scavenging and making it myself. Robot needs a new SSDD floppy drive? Flea market Commodore. RAM in the Soviet S100 clone going bad? Take apart a broken synth. Winchester drive controller going tits up? Drive around and look at all the junk bins of every computer shop in the county. Need to move a bit of kit but now the non-standard 45-pin cable is too short? Clip the ends off and Radio Shack them to RS-232. I also swapped a lot of gear around; The DOS machine that was used to program one robot was gradually upgraded from an 8088 machine to a 486 as I stole parts from it to keep the CP/M-86 one running.
The other thing I did a lot of was preventative maintenance. Blow out the dust, check the power supply, clean the disc drive, make sure everything is well seated. Switches got lubed, cables checked for faults, and media replaced.
.sig: Now legally binding!
the way they supported old lines at (major environmental controls company you've all heard of) was to keep all the old 286 machines and line printers in a back room the size of an 80s living room, and repair, repair, repair. label printing for boxes on the production line was old Printronics machines, which was the big headache.
if this is supposed to be a new economy, how come they still want my old fashioned money?
My employer has only recently taken off sale a re-shelled 1980s Object Pascal application that needed direct serial and parallel access and we were able to provide machines that handle it and the various peripherals perfectly well. Intel Reference boards (which they're withdrawing for PCs sometime soon unfortunately) and Startech PCI-E cards for the ports. I think the boards even have a floppy controller although the need for them was finally removed by an upstream supplier buying some CD burners a few years back.
Something written to work on 1987 grade hardware can sometimes run faster than intended on a Core i7, though.
I am running into the same problem supporting legacy systems. Finding older systems that will support the hardware you need, i.e. EBay is what we use to find older control systems and other hardware. I have found some software does not work well in a virtual machine environment. The original software sometimes needs particular OS (i.e. older dos versions or specialized OS versions). Hard drives fail and can be restored from Ghost images. Installing obsolete and unsupported software and software keys are sometime difficult to impossible to reinstall, not to mention the data lost. Serial ports are still available but ISA card slots are obsolete and are hard to find on new hardware. There are repair depots that will repair just about anything. Cost and downtime are a big problem if the parts can be fixed.
Best suggestion is to start to plan an upgrade to newer controls. There will be a time that some older hardware will fail and you will not be able to fix it. You will be forced to upgrade hardware immediately. If you have a plan to upgrade, the down time and cost to fix are substantially less in both investment cost and downtime. The older programs can be rewritten or converted to newer controls. The programs can be rewritten and ready to install when needed. This upgrade can save a lot of machine downtime. We have used this upgrade model more than once. This has limited our downtime to a couple of days for wiring and troubleshooting. Emergency programming of PLC and operator interface panels are at best very expensive on an immediate time frame. Learning new programming languages can take a long time to program efficiently. Extended machine downtime can be more costly than planned upgrades. Our management has been more open about planned upgrades after the first major downtime disaster.
Good luck in the trenches
Willie
.
There are companies that specialize in emulating "legacy" hardware systems. This usually means VAX/Alpha/HP3000 machines. But there is no reason it couldn't also be old PCs running DOS. The company I am most familiar with is Stromasys, but there are others as well.
Trivial to defeat,
Only if its UDP, and only if you dont care about return traffic.
Spoofing an IP is really only useful when you are flooding a target and really dont care about bi-directional communication, or if youre punching a hole in a firewall with the help of an intermediary server.
One of the few marketing catalogues I actually use. Sometimes flipping through a book can show you products you didn't know existed. http://www.iebmedia.com/
They are cheap, almost indestructible, small, low-power and ancient enough to comfortably run any legacy application out there, even under pure DOS. Should one break (which is, in itself, rather unlikely even for heavily used units), full service manuals are available and having lots of them means easy replacements. They have traditional, hardware RS232 and LPT ports, one of each. As long as you need a single machine for a single PLC, X40s should be one of the best tools for the job.
This is Slashdot. Common sense is futile. You will be modded down.
Vendors, such as Apple, Microsoft, etc, should be required to continue to support older software in their new hardware and OS releases.
There is no excuse, except greed, for them to drop support for Classic, Rosetta, PPC, etc. The new hardware, even a lowly iPodTouch, can easily emulate the old systems by orders of magnitude. There is a tremendous amount of not just mission critical software such as the above article discussed but also simply good software like what came out of the hay-day of educational software programming during the 1990's.
Apple and Microsoft have committed cultural and intellectual crimes by dropping compatibility such that older software can't run on the new OSs. They have HUNDREDS OF BILLIONS (yes, I'm shouting) of dollars and could not just afford but should be required to provide backward compatibility.
If they plan to stop providing backward compatibility then they should be required to give up all copyright, trademarks and patents related to the hardware, OS and software and provide full documentation five years before they sunset it so that others can pickup the software, OS or hardware.
I have two Windows98 virtual machines to support equipment requiring crusty old modems. They have been running trouble free for several years now.
Power off before disconnecting connecting connector. Seen on a cash register
we use these at work
http://www.moxa.com/product/nport_6150.htm
ethernet to serial they work very well for us
I am actually working with such systems right now! I've been trying to remote into an HP 1000 unit over serial but can't get the hyper terminal settings right to send the break command over and get going, it call comes out as corrupted. What has your experience been with this? We have no documentation for the manroland folks/ HP so I've been digging around.. happy to get communication back over MUX 0 to even see nonsense coming back from the terminal... Perhaps I can't use hyperterminal or ADVLINK so... I was very frustrated and happen to see your post! What are the odds? I was hoping for some terminal settings such as flow control etc for these things but have had no luck! Mostly we have been trolling around online to find legacy vendors that have amassed the stuff, to respond to your question.
Public Limited Company? Define your acronyms, moron.
I have a few hand wired 9 pin to 25 pin connectors with the CTS-RTS and DSR-DTR pins shorted together as they can simplify your life immeasurably.
Better be careful about shorting hardware flow control pins. I've seen CNC mills where someone did that. (Google "CNC Drip Feed"). The feeding PC didn't know the CNC controller buffer was full and kept sending data. When the CNC controller began accepting data again, it had missed hundreds of lines of code. The move commands drove the cutting tool into a bad place and people almost got hurt.
Your advice to learn RS-232 was excellent. But one must understand the flow control issues before you can know how to cable it.
Place nail here >+
My understanding is that the "web press" industry was / is almost entirely controlled with hardware based on the Motorola 68000 or 68030.
For those throwing out all kinds of Wintel solutions, the vast majority of them, in my experience FAIL the bit-endian conversion on a regular basis.
This is a question, not an answer, but one which I think could use some clarification.
IF it is Motorola 68000, yep you are in a world of hurt since Apple has tried repeatedly to kill that "line" out, regardless of the fact that I still provide support to people still running farms and small businesses on Apple IIe hardware. Replace the power supplies every five years and they just do not fail to simply work.
Elan 104 NC works with DOS and QNX and many flavor of Linux, comes with many Serial ports, USB, HDD, etc.
Industrial strength hardware, few years ago, they were much more expansive than a traditional PC.
http://www.farnell.com/datasheets/59590.pdf
Previously owned by Arcom Control Systems Inc., now owned by EuroTech inc.
http://www.eurotech-inc.com/
This one is still being sold among others with 2 working serial ports:
http://www.eurotech-inc.com/single-board-computer-geode-pc104-cpu1233.asp
Otherwise you can use a classic USB 2 Serial Port converter.
I've found lots of old hardware on ebay and it saves the bank too. The hardest problem I had was convincing Accounting to create an ebay account.
I occasionally have to interface with Square-D SyMax PLCs from the early 80s. We still have equipment at customer sites that's using it. The software we have to do the programming uses software timing loops so I have to use a 386 or early 486 laptop to run it. I have this very old 386 laptop with an 80 Meg hard drive that still hangs on and boots. I've warned my boss that someday it won't boot and we'll be done.
"Do the Right Thing. It will gratify some people and astound the rest." - Mark Twain
An RS232-to-Ethernet device is should be essentially a hardened Raspberry Pi running a modern Linux, configured for security. The communications should be established using ssh configured for login only using known keys. This can be set up relatively easily to be pretty foolproof and can probably beat 99.99% of commercial products out there when it comes to security. It's really not that hard.
A successful API design takes a mixture of software design and pedagogy.
I would go with one of the Ethernet based terminal server solutions. They are reliable and well proven.
Good point... You would need two way comms to get into most PLCs...
I have determined that my sig is indeterminate.
It's sounds like things are going well there.
It seems like if someone were to create a small 486 single board computer, similar to a Raspberry Pi, for under $60 or so, there would be an incredible market for it. For running everything from industrial equipment to a DOS/Windows retro gaming rig. Are there any cheap systems like this out there? I've seen lots of cheap ARM based boards but haven't come across any x86 ones.
The sending of this message pretty much inconveniences everyone involved.
"large printing firm", you might be in an antique world
I'm conceptually surprised by the title, the author complains about supporting antique software, then complains about hardware issues.
Tracy Johnson
Old fashioned text games hosted below:
http://empire.openmpe.com/
BT
RS232 is still routinely used in NEW PLC projects in modern factories. If you think this is "antique" you don't know much about the real world.
Before embedded web pages became de rigeur, configuring network equipment seemed so much more mysterious. And billable. I used to love the money received from tapping into customer's serial ports, but that's about all I miss.
-- Jimtown Kelly
I work in the exact same industry as you. I ended up getting our maintenance department mid range tough books with all the extra ports then I run virtual machines for xp down to ddoes. Works like a charm. If you need legacy ISA support you're SOL. You just need to tell everyone they have no choice but to upgrade. I did it and held my ground and got them to finally move on some of the testing equipment.
IT didn't choose this, or at least not in any case I'm directly familiar with. Industry as a whole has a huge number of PLCs which in general are programmed internally with ladder logic which interfaces with very old systems. These are the process controllers and flow controllers used in the chemical industry as well as industry in general.. As long as they work and are supported by the manufacturer or are simple enough to repair in-house, they will remain in service. I know of many systems still in service that were installed before I quit and went to college in 87. Those would be a minimum of 26 years old. If it works, don't fix it. Then you have Chromatographic integrators interfacing with data collection systems which can be another PITA
I am a PLC engineer, On the older systems, Siemens S5 I have found that running windows XP on a VM with the Helmholtz usb cable works pretty well. Most if not all of my dos applications run in windows XP. The only stumbling block I can see you running into is if you have some old GE series six plc's floating around. If I recall correctly they require a full-size communications card that plugs into an ISA slot. Given you can still get Mainboards with ISA slots on them I am not sure how more modern systems would support those 1970's and '80's hardware.
Hi.
I'm really lucky to have access to (generally) modern systems, but I feel my post is still relevant due to the nature of some of my work.
Often times, a matter (most of what we handle is copyright disputes) will have backup tapes. When it does, they are usually pretty old, unless the data is being provided by a company that is decently funded or actually cares about keeping records.
On more than one occasion, I've been given boxes of very very obsolete stuff.
There are a couple of ways we've handled this in the past. We have a guy who scours ebay every so often, and goes to various places in the state (and a few out of state) to look for *old* stuff. One time he scored a very old (late 80's) QIC tape drive. People wondered why we'd waste money on that, but about a year later we got a a really old pre-DLT tape that was exactly what we needed it for.
It's not a favorable solution, but it's the best one we've come up with: Acquire old hardware whenever possible. Especially when it's in half-decent condition.