that's a pretty tall order ... but ...
Greetings Hemang,
... BUT HAVE TAKEN 'INDUSTRIAL AUTOMATION' COURSE
I LEARNED ALLENBRADLEY, SIEMENS, MODICON IT WAS ONE WEEK COURSE
I hate to be the one to tell you this, but if you took just ONE course - for one week - then you did NOT really “learn” Allen-Bradley, Siemens, and Modicon ... that’s just way too much material to cram into a one-week course ...
BIG question: what PLC brand(s) are you going to be interviewed on? ... let’s assume (gosh I hate that word) that it’s Allen-Bradley and that your prospective employer uses RSLogix500 software as his programming language of choice ...
next question: did you get any “hands-on” practice with the RSLogix500 software during the class you took? ... let’s assume (and I still hate that word) that the answer is “yes, but very little” ...
if you’re still with me, then this is what I’d recommend ... download the free starter version of RSLogix500 software (click under the MicroLogix graphic on
this webpage) and get it running on your personal laptop ... if the interviewer will let you (maybe he will – maybe he won’t) offer to fire up your laptop right there on his desk and give him a guided tour of what you can do ...
now to be perfectly honest with you, the “deadline” that you posted for your interview doesn’t leave you much time to pull all of this together ... but if I were interviewing you, I’d personally be impressed with your “give-me-a-chance-and-I’ll-show-you” attitude ... but you’d darned sure better be able to pull it off ...
so let’s assume (man that word is killing me –where are the DETAILS that we need to adequately answer your questions?) that the job you’re interviewing for is as a maintenance technician – with a strong emphasis on electrical, mechanical, pneumatics, etc. ... as an interviewer the PLC skills that I’d personally find most impressive would be:
(1) the ability to nail down the PLC as just one part of the plant’s entire control scheme ... tell me that it’s a very IMPORTANT part, but that most of the problems are going to eventually turn out to be “field related” ... knowing how the PLC fits into the “big picture” is an important aspect of being able to troubleshoot the whole system ...
(2) the ability to troubleshoot the PLC inputs by just examining the LEDs on the input side of the PLC ... tell me that you don’t need a meter to tell whether the operator’s pushbutton is working or not ...
(3) the ability to tell whether a specific output is OFF or ON by just examining the LEDs on the output side of the PLC ... tell me that if the PLC’s output LED is already on, then it's a waste of time to fire up the laptop and “force” a bit to try to get the field device to turn on ...
(4) the ability to trace through some simple and then some more complicated rungs of ladder logic and identify which field conditions (and internal conditions, too) need to be “made” in order to turn on a specific output ... talk intelligently enough about “Examine If Closed” and “Examine if Open” to convince me that you really do know when to use one and when to use the other ... then discuss how rung conditions in “series” act as conditions that are “ANDed” ... and discuss how rung conditions in “parallel” act as conditions that are “ORed” ... and show me how you would use the software to go online with the processor and monitor these types of constructions during troubleshooting ... I’d find it very impressive if you could talk your way through a little “dog-and-pony” show on your laptop while you discussed all of these items ...
(5) the ability to systematically search through the ladder logic program and quickly find something like “Recirculation Pump” or “Part in Place Sensor” ... this has a lot to do with the “Find All” feature ... demonstrate how it will actually search the ladder logic program for words like “motor” in the description “Conveyor Motor A” ... hint: impress me with the knowledge that it’s usually better to search for something like “conv” – just in case the original programmer had misspelled “conveyor” as “conveyer” instead ...
(6) the ability to make temporary modifications to a rung for testing or troubleshooting purposes ... but be SURE to stress that you’re well aware of how DANGEROUS that could be if all of the system’s safety requirements aren’t considered ...
(7) the ability to “force” inputs and outputs and the significant safety aspects involved ...
so are we having fun yet? ... and others on the forum can certainly come up with some more items, but those would rank right near the top of my personal “must know” list ...
now let’s say that you follow the course of action that I’ve laid out above ... here are some BIG things that will still be missing from your “PLC-knowledge-repertoire” ...
(1) analog signals ... the free software won’t handle those ...
(2) going “online” (communicating) with the PLC for troubleshooting and monitoring purposes ... it’s hard to practice these IMPORTANT skills without having the actual hardware available ...
(3) skills required to download and upload programs (to and from) the PLC ... again, you need the hardware in order to adequately practice these skills ... but at least be sure that you know the difference between “upload” and “download” ...
and there are certainly others but these are likely to be the biggest concerns for most entry-level PLC technician jobs ...
warning! ... if this IS a job for a maintenance technician – then I’d suggest that you do NOT go into the interview and stress your ability to write a “traffic light” or “elevator” program ... just playing the odds will show that in most plants the PLC programs are already written ... and have been working for a long time ... but now SOMETHING in the field (wiring, electrical, etc.) has malfunctioned and the machine won’t run anymore ... the boss usually just wants you to be able to systematically track down the problem and get the machine working again ... he’s probably already got a programmer lined up (either on staff or an outside contractor) for projects which require programming skills ...
finally ... a word of friendly straight-from-the-shoulder advice ... realistically speaking, you’re probably not going to be able to pull this off (but see note below) ... you just don’t have much time available ... BUT ... if this opportunity doesn’t work out for you, there will most certainly be others in the future ... SO ... once this is over and all of the dust has settled down, do NOT just sit on your butt while you wait for the next “job interview” to come along ... instead, do everything that all of us have posted (and more) to get ready for the next chance ... and we’ll try to help if you’ll post specific questions ... but trying to cram in enough knowledge in just three or four day’s time is NOT the way to succeed at this game ...
one note of encouragement ... several years ago I had a guy call me up with the following story: he was getting out of the Navy in two days ... and his wife was going to have their first baby any day now ... and he had lined up a job interview in two weeks in Charlotte, NC (his wife’s hometown) for a job “with Allen-Bradley PLC skills” ... he told me he wasn’t even sure what “PLC” stood for ... but someone had told him that I’ve been known to teach PLC troubleshooting classes from time to time ... could I please help him? ... well, I’ll personally do anything possible to help out a veteran - so I invited him in for a free software “test drive” ... he brought his wife with him but they could only stay for about an hour ... she had to be taken to a doctor’s appointment ... (she looked like she could have delivered that baby right there in the lab) ... anyway ... we did the best we could in the time we had available ... he called me up about a month later and thanked me ... he had gotten the job ... he told me: “I was the only one that they interviewed who had actually TOUCHED the software” ...
so I wish you the best of luck ... and please come back and let us know how things worked out for you ...
