Orphaned PLC code

twu026

Lifetime Supporting Member
Join Date
Jan 2008
Location
Auckland
Posts
62
I got asked to make some modifications to an OEM machine by a client. The client does not have a copy of the PLC program & the machine manufacturer is not very forthcoming with providing any information or support.
So, I do what I dread the most - upload the PLC program and hack it.

Unfortunately, this is how PLC programs become orphaned. Some guy gets asked to modify the PLC without the original source code and has to hack the program.
The program running on the PLC then becomes different to the original commented code which makes that nice commented copy (on someones hard drive somewhere) obsolete.

Alas, you end up with an uncommented PLC code with some horrible hacks as the 'latest and greatest' version of source code.

The original programmer then promptly dis-owns this code because it is a horrible abomination of nature. The guys who did the hack has taken his money and disappeared (probably hiding in a hole because he/she is too ashamed of the crime he/she committed against code clarity).

The code is thus orphaned, forever shunned by all future programmers who see her.

I going back to hide in my hole.
 
Last edited:
Un-like you I am proud of the pathetic excuse hacking that I have done many times in the past, I think it has made me a better programmer

I am working on one now...he wrote the code very nice, I can tell just by what he did (even with out the documentation) the said part is just think of what I could of learned if I had the documentation...

It’s a dump on a peach packaging machine, wrote on a Automation Direct PLC, one thing I learned double spacing the NOP’s makes for good structuring habits, I do it now on all of my programs

I would of paid money to have a coffee and conversation with him...
 
I place the blame squarely on PLC manufacturer. I am sure they deliberately reduce the amount of memory and storage on their PLCs. I can buy 1GB of RAM for $20 (NZ) and a 2GB USB flash drive for $10 (NZ).
Yet you still see new PLCs coming out with memory/storage capacity in the kilobtye ranges.
It is a joke when you see that all that differenciates one model of PLC with another model PLC is a few kilobytes of memory. Cost to the manufacturer is an extra $0.05, cost to the buyer is an extra $200.
 
Amen...With memory cheap, it's a sin not to be able to store the documentation in the PLC.
 
Well, just for a change, to be fair to Siemens ...

in the newer 300 CPUs with MMC cards, if you choose a big enough MMC card (say 4 - 8 MB or so) then you can store your program and all your documentation (and any other files from your PC that you feel like) on the MMC, so there's really no excuse for not doing it. OK, the price Siemens charges for the MMCs is a bit of a rip-off, but in the context of the complete project cost, it's really peanuts.
 
If only life was perfect

While I agree with all the statments regarding storing the whole project inside the plc it is also reasonable to leave an SD card taped in the panel if you wish to be helpful to others coming behind you. (probaly get stolen by the first guy to open the panel once you have left)

I have seen many programs with missing comments/ partial comments but generally you can work it out if you know the operation of the machine
I remember the old days of AB PLC2 with the T3 terminal with no comments (not a feature) and even worse was a TI PLC where you had thumbwheels to select a program step and an led to tell you if that step had power flow... at least todays PLCs are so much better.

Cheers
 
Yeah but embedded PLC memory couldn't be much different than the solid state memory that a PC uses. I'm guessing that PLC manufacturers could sell devices with huge amounts of memory for almost no additional cost. The problem is that they would shoot themselves even more than their competitors since nobody has any need for "upgrading" from 256 to 512 Megs, for example. They can only support a tiered pricing structure if lower end devices won't do the job.

That's my conspiracy theory for the day ;-)

cjd1965 said:
While I agree with all the statments regarding storing the whole project inside the plc it is also reasonable to leave an SD card taped in the panel if you wish to be helpful to others coming behind you. (probaly get stolen by the first guy to open the panel once you have left)
 
twu026 said:
I place the blame squarely on PLC manufacturer. I am sure they deliberately reduce the amount of memory and storage on their PLCs. I can buy 1GB of RAM for $20 (NZ) and a 2GB USB flash drive for $10 (NZ).
Yet you still see new PLCs coming out with memory/storage capacity in the kilobtye ranges.
It is a joke when you see that all that differenciates one model of PLC with another model PLC is a few kilobytes of memory. Cost to the manufacturer is an extra $0.05, cost to the buyer is an extra $200.

Blanket statement, but go back and ask exactly WHAT PLC we are talking about.

Memory was not cheap at all 20 years ago, and more importantly, when Symax, S5's, PLC-5's, SLC's, etc were the ones out there, they didn't have the addressing space to handle a lot of memory, so every byte was important.

I spent $800 to buy a single megabyte of additional memory for a computer 20 years ago. It just doesn't compare with today.
 
rdrast said:
Blanket statement, but go back and ask exactly WHAT PLC we are talking about.

Memory was not cheap at all 20 years ago, and more importantly, when Symax, S5's, PLC-5's, SLC's, etc were the ones out there, they didn't have the addressing space to handle a lot of memory, so every byte was important.

I spent $800 to buy a single megabyte of additional memory for a computer 20 years ago. It just doesn't compare with today.

Very true. I remeber about 10-15 yrs ago offices were being broken into and only the ram was taken.. it was like gold dust
 
The newest horner PLC's have a compact flash slot that can used as data collection and other storage. I know you can load the programs from the drive I am sure you could load a file on to the card as well.
 
I am not convinced that these removable storage cards are the best way forward - think long term, think 10+ year.
There is so many different types of cards out there (CF-I, CF-II, SD, microSD, miniSD....). Every few months there is a new format which is physically smaller/different and holds more storage.

Lets fastforward 10+ years down the track, do you think anyone will still be using SD cards or CompactFlash cards? People will probably have 100+TB cards by then (just a wild guess).
How many laptops will have a built-in SD card or CompactFlash reader?
What happens when the PC industry moves on from these formats and stop mass producing SD cards or CompactFlash?

They become extremely expensive, like those bloody PLC cables! $1000 for a new 512MB SD card?!

How much is it going to cost a PLC manufacturer to add 1GB of internal flash memory to a PLC? Maybe $5 max, that is my point.

It cost them peanuts to add internal storage to PLCs, but they deliberately don't. Forgot storing the PLC program on SD or CompactFlash cards, lets bust out the EPROM programmers and UV erasers.
 
Last edited:
While I agree with all the statments regarding storing the whole project inside the plc it is also reasonable to leave an SD card taped in the panel if you wish to be helpful to others coming behind you. (probaly get stolen by the first guy to open the panel once you have left)

I am not convinced that these removable storage cards are the best way forward - think long term, think 10+ year.
There is so many different types of cards out there (CF-I, CF-II, SD, microSD, miniSD....). Every few months there is a new format which is physically smaller/different and holds more storage.

Both these points are reasons why it makes sense to spend a little more money on a suitably sized MMC card, if you're using a 300 series CPU, to store the program and all relevant documentation on.

The CPU won't run without the MMC card, so it's extremely unlikely to get stolen and I would guess that at least part of the extortionate price that Siemens charges for these MMCs is funding the fact that you'll still be able to buy them in ten or fifteen years time.
 
The new Omron PLCs CJ&CP come with build in memory card for documentation.
I find it great feature for other programmer who connect to the machine.And have all in hand.
 
robertmee said:
Amen...With memory cheap, it's a sin not to be able to store the documentation in the PLC.

I brought this up 5 yrs ago when I came into this industry from DDC/BMS. For such expensive high quality equipment I cant believe how backward (some) of the software and memory capabilities are. It was unheard of to have synonyms/projects not stored on the device itself.
Anyway that was 5 yrs ago, I quess I have just got used to it now.
 

Similar Topics

Hello, I'm trying to delve a little into rs-485 communications for a couple projects of mine. Until now I've been using a delta vfd and a delta...
Replies
1
Views
13
Greetings All, I recently decided to start freelancing in Controls and Automation part time, most of my experience has been with Rockwell...
Replies
2
Views
55
I am having a problem communicating my PLC with Drive via Modbus connection. I start by opening the port and there is no problem, but then when I...
Replies
5
Views
38
I have worked on small projects using AB Micrologix but now we want to take a photo, process it online, and sort based on returned variables...
Replies
1
Views
81
Hi, I have a 1500 that controls a station with diferents warehouses, but i also have a 1200 that controls one of those warehouses, i have been...
Replies
9
Views
203
Back
Top Bottom