View Full Version : lost in plc's
June 6th, 2002, 03:06 PM
Greeting from plannet plc,
Ok I guess I'm frustrated now.
I am trying to find out what kind of advanced functions plc's have so that I can see the range and evaluate the types, any suggestions?????
I would be really greatfull to anyone who can tell me what this is all about!
June 6th, 2002, 03:12 PM
That is a really open ended question. That is a really long list.
Tell your instructor that in the real world, most people determine what the task requires and then evaluate the hardware that is capable of doing it. This narrows it down a lot.
June 6th, 2002, 03:20 PM
all of the questions are open ended Its just trying to understand what he really wants I dont have time to ask him as it project has to be finished and handded in, in 4 days :(
June 6th, 2002, 03:33 PM
The problem is, each manufacturer defines for itself what consitutes an "advanced" function.
For some, the ability to calculate SIN(x) (or even SQRT(x)) is
"advanced", while others just consider that a normal math function.
Or even data types - long integers, 8-byte floats.
For others, it's support of multiple IEEE 61131-3 languages.
Other's brag about the control over the RS-232 port, while other's practically ignore it.
Basically, a PLC is made to manipulate bits (cols & contacts), and have a few timers and counters. Anything above that may be considered fru-fru.
I do hope you aren't going to be expect us to do all your homework for the rest of the semester. If your prof keeps asking these sorts of open-ended, irrelevant questoins, call him on it. Ask for clarification. Remember, you pay HIS salary. He's there for you, not you for him. If he doesn't deliver, drop the course, and complain to the dean. Try to convince former fellow students to do the same. I know it's tough to do if it's a required course, but unless there is an environmental pressure to change, he won't. Think Darwin.
June 6th, 2002, 03:39 PM
So basically any function which the manufacturer see's as a bit speacial would be considered an advanced function! that makes sense, I on the right course now I think, I hope so anyway. Otherwise 4 years of studying could all come to a big crash and so could my carrer.
Thanks for replying
June 6th, 2002, 05:31 PM
I'd like to add that defining "advanced functions" is shooting at a moving target. At one time any PLC that had analog I/O and four function math was considered "advanced". Then anything with serial communications and networking ability was advanced. Then anything with floating point math and PID blocks was advanced. Then anything with high level language ability like "C" was advanced. Then anything with ethernet was advanced. And now most of these features are available in all but the smallest brick PLCs.
Essentially, to an end user any feature that the majority of PLCs in a specific market segment don't have is advanced. To a salesman any PLC with features they didn't sell last year is advanced. To a purchasing agent any PLC that costs more than he paid last year had better be advanced!
What is advanced? How high is up?
June 6th, 2002, 09:39 PM
Last I saw an Advanced Function, it detected the forward movement of a trolley.
Guess some of us are less sofisticated.