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"All PLCs are the same"... What do you think?

32 posts in this topic

Make friends with the electricians and mechanics. When they are troubleshooting something, go out and help. At first, don't touch anything. Ask questions and help them come to the answers themselves. Before you even touch a screwdriver, ask for permission first. Then jump right in! You will very quickly develop an amazing amount of support from the front lines. After you do this for a little bit, you will find that you can ask for things that the rest of engineering can't actually get done, ever. People want to help you because they consider you a resource and not a road block. Once you've done this for a little bit, even if you get a little heat from your boss, then begin backing off. You've established yourself as a knowledgeable expert and not just another engineer. You will be called on if they truly need you but they will let you go back to being an engineer after that point. Further, looking at the situation from a million miles away and just two paragraphs, I get the impression that your boss doesn't really understand control systems either. And after several statements and "white lies", he may have a huge trust issue. You are experiencing the fallout from it. On top of that, there may be a real lack of skill and knowledge within the maintenance department. If you have a bunch of guys that are cutting corners like you described, then perhaps you are often better off with contractors than doing it in-house. The way around this is to start with small projects and a few incidents once in a while. Use probing questions to lead someone to the answer instead of doing it for them. Then slowly introduce small projects into the electric shop yourself to be done in-house. As you build confidence all the way around, you will become less reliant on contractors. And you are building your own reputation. Even if a plant electrician's rate (fully costed) is say $35/hour, even with overtime, they cost you $52.50, which is often less expensive than contractors. So if you negotiate deals where you get volunteers for overtime, it is probably less than contractor T&M rates. You get ownership (since we built it), and you expand the knowledge and skillsets. But it takes some management on your part to see when and where this can be a viable option. Right now I've got a $150K controls project going in. I'm having the day shift electricians wire up panels and a couple off shift guys install on overtime. Contractors are running conduit simply because there just isn't enough in house labor to get the job done and everyone is happy with this arrangement. I keep getting told that "we've never done anything like this before". I made prints and checked all the interconnects before we started and made pretty detailed drawings of everything. At first, maintenance pushed back because they were overwhelmed with the scope of the project. So I asked them to work on one panel at a time and worked hand-in-hand for at least a few minutes with the electricians on each panel getting started, laying it out, etc. Maintenance supervisors were nervous as hell but now their hourly guys are telling them that this thing is straightforward and easier than the rest of the stuff. So everyone is building confidence. The project will be more successful than normal because as they are building it, they are learning how it works. I'm confident that troubleshooting (ease of maintenance) will be improved when we get done. I'll bet your boss never tried anything like this. So your department is looked on as a necessary evil. Not part of the team. Team building takes time and effort. If done right, you won't be the "troublemaker" anymore. You'll still have an outspoken reputation and all that, but nobody will hold it against you if you are perceived as a leader. If you get the reputation as a road block, then you pretty much are done. Anyways...somewhat long winded but it's the approach I use. I've had a $50K burner safety system installed in house, built to code, which would "never work" and "always fail" and all kinds of other excuses for why we couldn't have a real safety system in place on a 30MBTU/hour plus burner. And that it would all have to be contracted out. It's still functioning the same way that we installed it on day #1. And it was done with about 50% in-house labor. It's very easy to maintain and works reliably, so everyone likes it and makes efforts to keep it operating. It just took some negotiations and putting plenty of thought into the design up front.

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I think you hit the nail on the head with this one.. My first "venture into the unknown" is with a GE 90-30 PLC that has been programmed by a contractor that used reasonably current software.. They just handed me a laptop with 4-year-old software on it and, big surprise, it won't open his project!

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Yep, yep, yep... BTDT and bought the T-shirt... along with the software to debug an ancient PLC-2. I'm still waiting for management to buy me the RSLogix 5000 software to support one machine we bought 2 years ago. Even when you only have one hardware vendor, you still need to buy & upgrade multiple pieces of software on a regular basis. Today, I'm bowing to the CFO who said to go ahead & renew my Autocad support contract for another year... Gravitar - you may be able to get away with downloading the program from the machine & then creating a description text file to merge into it. It's the long way around, but will accomplish the same goal of documenting the machine.

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I just spent a good long while this morning trying to do just that. I might be approaching this from the wrong mindset, but I just didn't see how you could walk up to an "unknown" processor and capture the program! Anyone know how to do this? I'm using Cimplicity Machine Edition v. 5.0. Just to add insult to injury, the online help system in this particular installation doesn't work, either. It seems to want to go to the web to find the help files, but I'm having no luck getting it to penetrate the company's firewall, nor can I seem to be able to reconfigure it to use local help files.

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CME's help system isn't much help when it does work. If you can figure out the right search term, you get to see either the help page or your logic/graphics. I've never noticed help trying to access a web server instead of local files, so I can't help you there, but uploading a program isn't too hard. 1. Create a new project with whatever name you want to use for that machine and a template matching the PLC type. Don't worry about the hardware details, they will come in the upload. 2. Select Target1 and set the physical port to match your connection to the PLC. 3. Go online with Target1 and upload everything - configuration, logic and data. You will be prompted about overwriting the existing target configuration but that's OK. 4. You now have the current PLC program with no documentation. Machine Edition will automatically assign variable names using the reference addresses the first time an address is used, and blank rung comment numbers will appear in the ladder logic (the pointers are saved in the program). 5. Now the fun starts, as you attempt to reverse-engineer the documentation from the I/O, instruction data maps and (maybe) the HMI. Finally, the files need to be where anyone can find them. One large plant where I did some work kept a floppy disk with the latest program in each control panel with a PLC, so that an electrician on any shift could take his laptop and go online for troubleshooting. What our larger clients do now is get all of the PLC's tied into one network and use Cimplicity (now Proficy) Manager. It understands most major brands in addition to GE Fanuc, and puts your code on a server, from which the programmer checks files in and out. I'll skip the joys of bridging Ethernet to Modbus Plus and Data Highway Plus.

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Thanks for the tip! I did somehow convince management to provide me with the latest rev, so that hurdle is crossed. It looks like even with this newer version though, it is trying to find help files from an external server.. Very inconvenient!

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GE Fanuc put the last set of true "manuals" online back in about 2004. Now they only publish everything in help files. Fortunately, version 4-5 is the time period when those manuals were still relevant. Go to http://globalcare.gefanuc.com/ and you should be able to easily download the manuals. The tech notes require a "globalcare" license but the manuals are public. If there's a tech note that you really, really have to have, I may be able to get it for you.

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