Tying to switch careers from electrician to electronics, PLC question? - Page 1
Forum section: electronics / general

author: rwgast_lowlevellogicdesin
author_rank: Frequent Contributor
timestamp: June 22, 2015, 06:49:24 pm
content: So im worked as an electrician for a few years and I've been layed off for a year as a single father and my unemployment is going to run out soon. Ive had some reasonable job offers in the electrical field but I am looking twords a more technical job than just installing breaker panels and lights, or solar work! Most of my career has been commercial or industrial green energy.Ive been looking at jobs online and one of the major components in alot of them is PLC work. I understand a PLC is basically a micro controller with isolated I/O using opto-coupling and or relays so you can connect "Highe Voltage" Loads to them! I also understand there programmed in latter logic, being an electrician i have never had to program a PLC on the job just connect wires to it.I would hate to limit my job options because I have never programmed a PLC, and I don't have one laying around or extra funds to just buy one. How hard is it to actually learn latter logic, I am thinking maybe I can use an emulator to learn and fudge the resume a bit... Also how different do PLCs vary from brand to brand?I feel comfortable with embedded work using AVRs, Propeller Chips, and a little STM32 stuff. I understand micros enough to program them with C and no abstraction layers, but im not sure how that will help me in an industrial job that is basically instrumentation on equipment and dealing with PLCs

author: nctnico
author_rank: Super Contributor
timestamp: June 22, 2015, 06:58:27 pm
content: Nowadays PLC programming is also done in higher level languages like Siemens' STL and SCL. There is quite some demand for people who are good with programming PLCs beyond doing simple ladder diagrams. Someone I know is literally flying around the world to do PLC programming jobs.

author: B.B.Bubby
author_rank: Regular Contributor
timestamp: June 22, 2015, 07:29:54 pm
content: Go and buy a cheap programmable relay, plenty out there for under $150.Not really a proper plc and you can pretty much only program them in ladder or function block shit.I've been a sparky for 25 years, pretty much all high end machines I work on are programmed in C or a structured text type language (pascal-ish) B&R Automation. It's a job for a professional software engineer to totally fuck up the software in these things.You'll never see a job for an electrician that requires programming in anything other than Ladder or ST.If you do need to do some programming it'll usually be for a simple custom control circuit / monitoring etc.Ladder sucks big time, but it's the industry standard for programs written by electricians.Just stick to the basics with the PLC stuff. Study up on the safety regulations concerning machine control. Study up on VSD drives etc.Unless you have an uber brain for programming and extensive industry experience, the money is with been a good all rounder.

author: B.B.Bubby
author_rank: Regular Contributor
timestamp: June 22, 2015, 08:12:15 pm
content: Quote from: nctnico on June 22, 2015, 06:58:27 pmMy job pretty much involves flying around the world fixing programmers stuff ups. Never seen a software engineer leave their air-conned ivory tower ever! Just leaving New Caledonia now due to a dodgy PID implementation that burnt out numerous heating elements.

author: LabSpokane
author_rank: Super Contributor
timestamp: June 22, 2015, 08:32:38 pm
content: If you want to get into PLC programming and want to learn ladder logic, one cheap-ish way to start is with Automation Direct:http://www.automationdirect.com/adc/Shopping/Catalog/Programmable_Controllers/DirectLogic_Series_PLCs_(Micro_to_Small,_Brick_-a-_Modular)I'll bet you can find a bunch of examples on eBay cheap. They are crude, they are not Allen Bradley or Siemens, etc, but it will be a start. Ladder logic is an anachronism, but there are plenty of places looking for someone who can do it.You will likely be able to find lots of "big name" PLCs on ebay as well, but the issue will be getting the programming software for them.================================Like has been mentioned, look into how safety systems, etc have to be designed. There are all sorts of peculiarities for how two-hand controls, e-stops, light curtains, etc must be wired to be legal. And I don't know where you live, but a lot of this is location dependent.For example, in the US, it is illegal to use a signal into a controller for an emergency stop function. In Japan, they do it all time, or at least every robot I got from Japan, the e-stop was just a signal line into the controller.That's just an example. If you can walk into an interview and be street smart about that kind of stuff - you'll get a good job.===============================And I just checked, there are several DL105 on eBay for under $100. There's a brand new one for $99/obo. These also go under the brand-name "Koyo", so check for that as well. I even saw a 205 with modules on there.The software is a free download from Automation Direct with a 100 word download limit. That should be enough to start. I also saw a copy of programming software on there. I'm not sure if there is registration or copy protection on it now. Historically, there hasn't been. You will also need a programming cable, which is just a DB-9 to RJ-11 cable.

author: briselec
author_rank: Regular Contributor
timestamp: June 22, 2015, 08:44:52 pm
content: By the sounds of it you'll pick up programming and troubleshooting using ladder logic very quickly. It's certainly not hard which is why it exists. Once you know how to program one brand of PLC you can easily program others. I believe the Click PLC sofware is free to download.Have a look athttp://forums.mrplc.com/for lots of stuff about PLCs.Also you should read up on the different types of industrial sensors, how to set up VFDs, how the PID algorithm works, SCADA( usually only found in the bigger factories), the difference between a stepper motor and a servo, the different types of encoders, the different types of networks used, etc.Having the extra knowledge from working with embedded systems can make the difference between being an average industrial sparky and being a really good one.

author: Fat_Lab
author_rank: Newbie
timestamp: September 24, 2015, 12:38:05 pm
content: At my work the PLC programming and HMI programming is strictly done by engineers. The electrical field service people do all of the installing, terminating and point to point testing. You are not limited by not having PLC experience. You should see about working at a company that provides PLC solutions.

author: retrolefty
author_rank: Super Contributor
timestamp: September 25, 2015, 03:01:56 am
content: Yea, it's called ladder logic not latter logic. So called as the programming language/interface was designed to mimic electrical wiring drawings with all the components connecting left to right between two power rails. It allowed experienced electrical power and control engineers to do the programming rather then having to write up requirements and hand off to more traditional programmers. As stated most modern PLCs offer more powerful programming methods in addition to the simple ladder (not latter) method.At the refinery I worked at the Instrumentation/controls technicians took care of all the PLC installation, troubleshooting, and repair. The electricians worked on the 440 volt and up stuff (motors, breakers, etc).

author: bills
author_rank: Frequent Contributor
timestamp: September 25, 2015, 03:33:31 am
content: To answer the ops question, PLC programming is not something that you can learn in a couple of days.Most all of the software is different and expensive (the allen bradley software is about $2000.00) and is not hackable .The best way would be to check out some classes in industrial automation there are several adult edu. classes in my area I assume you are in the US ?I worked with allen bradley and ge furnac PLC's for the last 25 years and I am only a fair to poor programmer,most of my work was in fine tuning existing programs this can be learned very quickly but writing new ones takes more experience.When you apply for a job let them know your experience with mirco controllers and you could get lucky.One of best ways to learn is to work with someone who does this and is willing to train you.BTW does any one still use a AB plc 5?Check out the link briselec has in his post there is a link to a demo for allen bradley rs logic 500 A great learning tool.

author: bills
author_rank: Frequent Contributor
timestamp: September 25, 2015, 04:55:55 am
content: @LabSpokanethat is some interesting info about the inputs for shut down, does that apply to our northern neighbors? Canada .we had some extendable conveyors that had the shut down at the operator station that used an Estop input to stop the conveyor but at the control panel some 30 feet away the e stop killed the power to the plc and the entire unit except the motor brake.

author: LabSpokane
author_rank: Super Contributor
timestamp: September 25, 2015, 05:21:35 am
content: Quote from: bills on September 25, 2015, 04:55:55 amI honestly don't know about Canada anymore. My experience when I was working in Canadian shops that the safety systems and procedures were always as-good or better than anything in the US. But, we also had the Japanese robots up there with the non-compliant e-stops.And your description of the conveyor e-stop sounds like the second e-stop was incorrectly wired into a PLC input only. The control panel one sounds correct to me. It all comes down to the definition of "safe." I don't think there's anything inherently wrong with an operator button that stops a piece of equipment on-demand, it's just that an e-stop should mean "something is very wrong, stop the equipment as safely as possible."It's like machine guarding. I was just having a conversation with our safety engineer a few weeks ago. He actually requested a company *remove* guarding from a conveyor section because the guarding actually increased the hazards to an operator. (pinch points)It really takes a dedicated expert to make it through these safety standards, particularly when going into an unfamiliar market. The standards change and I'm sure what I knew to be "correct" 15 years ago is outdated.