revlution4
Member
- Location
- North Dakota
Just wondering what the recommendations are out there for learning about PLC's, textbooks or online and who? Thanks!
Programmable Logic Controllers
- Thread starter revlution4
- Start date
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MAC702
Senior Member
- Location
- Clark County, NV
Can't give a review because I don't work with them, but my book is the one the local union uses to teach them: Frank D. Petruzella's Programmable Logic Controllers 3rd Edition.
I have to keep reminding myself that 2005 was a significant time ago when it comes to technology, though.
I have to keep reminding myself that 2005 was a significant time ago when it comes to technology, though.
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
171031-0824 EDT
revlution4:
A PLC in its earliest form was a stored program digital computer using a specialized language that simulated relay logic for control of something.
Today PLCs have been extended to perform many other functions than just logical circuits, such as math functions.
You need to know how to design or work with logical circuits. This means knowing how to work with AND, OR, NOT, timers, retentive memory, and transitional contacts.
The truth tables for AND, OR, and NOT describe their function. The word OR usually means inclusive. Meaning any one or more inputs to an OR will produce an output. An OR or AND can have many inputs. There is also an exclusive OR written as XOR and is only a two input function. The XOR produces an output only when the two inputs are different, and no output when the inputs are the same.
You will probably learn more by buying an inexpensive PLC, studying its manual, and creating programs than by trying to study some text book. There are some functions that will be common to all PLCs and others that are unique to specific PLCs.
For ordinary machine control logic I would never use a PLC in a sequencer mode, use only combinatorial logic.
Sequential mode should only be used where it uniquely fits the application, and that is not in a general machine application.
Learn about logical circuits first, then study a specific PLC.
You will learn the most and quickest from hands on experience.
.
revlution4:
A PLC in its earliest form was a stored program digital computer using a specialized language that simulated relay logic for control of something.
Today PLCs have been extended to perform many other functions than just logical circuits, such as math functions.
You need to know how to design or work with logical circuits. This means knowing how to work with AND, OR, NOT, timers, retentive memory, and transitional contacts.
The truth tables for AND, OR, and NOT describe their function. The word OR usually means inclusive. Meaning any one or more inputs to an OR will produce an output. An OR or AND can have many inputs. There is also an exclusive OR written as XOR and is only a two input function. The XOR produces an output only when the two inputs are different, and no output when the inputs are the same.
You will probably learn more by buying an inexpensive PLC, studying its manual, and creating programs than by trying to study some text book. There are some functions that will be common to all PLCs and others that are unique to specific PLCs.
For ordinary machine control logic I would never use a PLC in a sequencer mode, use only combinatorial logic.
Sequential mode should only be used where it uniquely fits the application, and that is not in a general machine application.
Learn about logical circuits first, then study a specific PLC.
You will learn the most and quickest from hands on experience.
.
- Location
- Bremerton, Washington
Rockwell Automation has the best training, however it is specific to Allen Bradley PLCs.
Expect to pay $600 a day.
https://www.rockwellautomation.com/global/products/training/overview.page?
What I would recommend is to take a basic two day class, then get your hands on a PLC and practice programming.
AB has a nice book about $10 called MicroMentor, it may be out of print, but well written its meant to go along with their Micro Logix PLC line, in particular the ML 1000 series.
A DC version of a ML1000 is about $100, and the starter software is free
here are a couple of good plc forums
https://www.mrplc.com/
http://www.plctalk.net/qanda/
Koldwater Technology has some good interactive DVDs
And again I want to emphasize that you must have hands on to learn PLCs, book learning is not enough!!
Expect to pay $600 a day.
https://www.rockwellautomation.com/global/products/training/overview.page?
What I would recommend is to take a basic two day class, then get your hands on a PLC and practice programming.
AB has a nice book about $10 called MicroMentor, it may be out of print, but well written its meant to go along with their Micro Logix PLC line, in particular the ML 1000 series.
A DC version of a ML1000 is about $100, and the starter software is free
here are a couple of good plc forums
https://www.mrplc.com/
http://www.plctalk.net/qanda/
Koldwater Technology has some good interactive DVDs
And again I want to emphasize that you must have hands on to learn PLCs, book learning is not enough!!
kwired
Electron manager
- Location
- NE Nebraska
If you can understand ladder logic diagrams you already know quite a bit of what you will need to know. Proper syntax and other procedures is most of the rest and can have some variances between units. This gets you through for most basic programming functions, there can be more complex functions but they are explained in users manuals and help pages in the software help files. As mentioned you might be better off buying an inexpensive controller and learn just by playing around with some of your own mock programming.
Automation Direct has some Clic PLC's you can purchase for under $100. Their program software is free and downloadable from their site. In fact you can write all the programs you want with the software and even check it for syntax type errors, but to be able to actually have an output react to input conditions you really need to load that program into the controller and run it.
Automation Direct has some Clic PLC's you can purchase for under $100. Their program software is free and downloadable from their site. In fact you can write all the programs you want with the software and even check it for syntax type errors, but to be able to actually have an output react to input conditions you really need to load that program into the controller and run it.
- Location
- Bremerton, Washington
Also I forgot that the trend in PLC communications is TCP/IP (Ethernet), learn as much as you can about Ethernet, routers, switches, subnets, domains,....
If you have the opportunity to take a trip to Charleston, SC I highly suggest you take a class at Ron Beaufort Training, LLC , you will not be sorry.
You can get a very good idea of his GREAT ability to teach by reading some of his posts at PLCs.net, just search for Ron Beaufort.
I personally have taken a cople of his classes and have always wanted to go back and take a PID class but never made it.
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revlution4
Member
- Location
- North Dakota
Thank you all for the replies, I will do some more research into the various items. I do understand some basic ladder logic, I just need to expand on it more and implement it.
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
171031-2124 EDT
revlution4:
From your last post it seems that your basic need is to understand logical circuits.
Suppose you have four binary signals A, B, C, and D. Binary signals are two state signals. Variuos names are assigned to these two states. Typical names are TRUE and FALSE, 1 and 0, CLOSE and OPEN, etc. Various logical functions are defined by what is called a truth table. So signal A can be either T or F, and the same for the other logical signals.
A truth table for two inpits has 4 possible input combinations. 00, 01, 10, and 11. The truth table for AND has a 1 for its output only when both inputs are 1s. Whereas an inclusive OR, usually described by the word OR, only has a 0 output when both inputs are 0.
Note that the logical function NOT is a single input function where the output is the opposite of the input.
If we have a logical signal A, then the NOT of A is often written as /A or A with a bar over it. If we write a logical equation like A and B and NOT C = D, then D is true only when A and B are true, and C is NOT true.
So an electrically latched relay could be described as :
A or ( D and NOT C ) = D
where D is the output.
If C is not asserted, meaning NOT C is TRUE, and A is asserted momentarily, then D remains on after A is lost because of the parallel path, the OR function, maintains D on. D can only be dropped out if C is asserted making NOT C a 0 while A is still not asserted. Sounds like double talk, but try thinking this way.
To create an exclusive OR function write ( A and NOT B ) or ( NOT A and B ) = D
.
revlution4:
From your last post it seems that your basic need is to understand logical circuits.
Suppose you have four binary signals A, B, C, and D. Binary signals are two state signals. Variuos names are assigned to these two states. Typical names are TRUE and FALSE, 1 and 0, CLOSE and OPEN, etc. Various logical functions are defined by what is called a truth table. So signal A can be either T or F, and the same for the other logical signals.
A truth table for two inpits has 4 possible input combinations. 00, 01, 10, and 11. The truth table for AND has a 1 for its output only when both inputs are 1s. Whereas an inclusive OR, usually described by the word OR, only has a 0 output when both inputs are 0.
Note that the logical function NOT is a single input function where the output is the opposite of the input.
If we have a logical signal A, then the NOT of A is often written as /A or A with a bar over it. If we write a logical equation like A and B and NOT C = D, then D is true only when A and B are true, and C is NOT true.
So an electrically latched relay could be described as :
A or ( D and NOT C ) = D
where D is the output.
If C is not asserted, meaning NOT C is TRUE, and A is asserted momentarily, then D remains on after A is lost because of the parallel path, the OR function, maintains D on. D can only be dropped out if C is asserted making NOT C a 0 while A is still not asserted. Sounds like double talk, but try thinking this way.
To create an exclusive OR function write ( A and NOT B ) or ( NOT A and B ) = D
.
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
171101-0636 EDT
Continuing from last night.
IF I have a simple relay circuit with one normally open pushbutton spring return switch contact in series with a relay coil and a source of power, then whenever the pushbutton is pressed in the relay coil will be energized and a normally open relay output contact will close. The output contact will only be closed while the input switch is closed (held in).
Call the input button A and the relay output D, then D = A.
Take the normally open relay contact, D, and put it in parallel with the input contact A. Before power is applied to this circuit A = 0, and D = 0, because D is de-energized.
Apply power to the circuit, and D is still equal to 0, because both A and D are open, and there is no power path to the coil of D.
Next momentarily press the button A and this energizes the relay closing contact D. The normally open, but now closed D now provides a parallel path of power to coil D around the A contact. Releasing A to its normally open state does not drop out the relay D because the D contact maintains power to the relay coil. The relay D will never drop out until power is some how removed.
Add a normally closed pushbutton C in series with the D contact. So long as C is not pressed in, asserted, the above relay circuit will remain energized once initially energized.
If A is not held in, then asserting C, opening the C contact will de-energize the relay D, and power to the whole circuit did not have to be removed to drop out the relay. Releasing normally closed pushbutton C does not reclose D because D is now open, and A is also open.
This is a simple two pushbutton relay control circuit.
.
Continuing from last night.
IF I have a simple relay circuit with one normally open pushbutton spring return switch contact in series with a relay coil and a source of power, then whenever the pushbutton is pressed in the relay coil will be energized and a normally open relay output contact will close. The output contact will only be closed while the input switch is closed (held in).
Call the input button A and the relay output D, then D = A.
Take the normally open relay contact, D, and put it in parallel with the input contact A. Before power is applied to this circuit A = 0, and D = 0, because D is de-energized.
Apply power to the circuit, and D is still equal to 0, because both A and D are open, and there is no power path to the coil of D.
Next momentarily press the button A and this energizes the relay closing contact D. The normally open, but now closed D now provides a parallel path of power to coil D around the A contact. Releasing A to its normally open state does not drop out the relay D because the D contact maintains power to the relay coil. The relay D will never drop out until power is some how removed.
Add a normally closed pushbutton C in series with the D contact. So long as C is not pressed in, asserted, the above relay circuit will remain energized once initially energized.
If A is not held in, then asserting C, opening the C contact will de-energize the relay D, and power to the whole circuit did not have to be removed to drop out the relay. Releasing normally closed pushbutton C does not reclose D because D is now open, and A is also open.
This is a simple two pushbutton relay control circuit.
.
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Don't know if you had a chance to visit the link I provided but if funds are not available right now I suggest you take a look at Ron's FREE stuff. He has some sample lessons, quizzes and links to his YouTube series that are very informative. Just click the "Sample Lessons & Videos" link on his main page.
Good luck! :thumbsup:
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
many community colleges have PLC classes. usually not for credit but they are usually inexpensive and pretty good.
relay ladder logic is the common language for most PLCs. It is not exactly the same from model to model but is pretty close. learn it once and it readily transfers to other brands.
buy something cheap to practice on. you can get a clic from automation direct for $100 with free software.
even ab has small plcs with free software these days.
relay ladder logic is the common language for most PLCs. It is not exactly the same from model to model but is pretty close. learn it once and it readily transfers to other brands.
buy something cheap to practice on. you can get a clic from automation direct for $100 with free software.
even ab has small plcs with free software these days.
b1miller
Member
- Location
- Washington
- Occupation
- Electrician/Electrical Administrator/SCADA Engineer
My approach to learning PLC programming
My approach to learning PLC programming
Back in the 90's i bought a used Allen Bradley Micrologix 1000 from EBAY for $75.00 and then downloaded the free RSLogix lite and Linx from the AB website. I then built a small trainer with input switches and output LED's and I was off to the races. My company sent me to the AB programming classes later and with a lot of help from our company engineers I was able to become proficient in the AB software. Network proficiency definitely will help.
My approach to learning PLC programming
Back in the 90's i bought a used Allen Bradley Micrologix 1000 from EBAY for $75.00 and then downloaded the free RSLogix lite and Linx from the AB website. I then built a small trainer with input switches and output LED's and I was off to the races. My company sent me to the AB programming classes later and with a lot of help from our company engineers I was able to become proficient in the AB software. Network proficiency definitely will help.
- Location
- Bremerton, Washington
That's kind of what I suggested. But get the MicroMentor book has practice exercises
Eh40
Member
- Location
- Connecticut
PLC
PLC
You can find inexpensive plc controllers out there, a free software download of a PLC emulator would be good ( at this learning level, scan (PLC) versus deterministic (PC) should not be an issue, so a PLC emulator running on a PC, should be a good free learning tool) In essence basic ladder logic, is relay logic where the output coil would be the same as a coil on a relay, and the contacts would follow the state of the relay. 2 things you may want to consider, 1) each vendor has its own programming software used to program the ladder logic, typically unique to its product, 2) Some PLC'S have several programming languages, with ladder logic being one of the easiest. Are you looking to design systems, or an understanding of how to install, startup and maintain , as these would be 2 different directions. I was a corporate trainer for PLC and other industrial control systems for over 10 years ,training electricians and engineers ,and happy to provide insight.
PLC
You can find inexpensive plc controllers out there, a free software download of a PLC emulator would be good ( at this learning level, scan (PLC) versus deterministic (PC) should not be an issue, so a PLC emulator running on a PC, should be a good free learning tool) In essence basic ladder logic, is relay logic where the output coil would be the same as a coil on a relay, and the contacts would follow the state of the relay. 2 things you may want to consider, 1) each vendor has its own programming software used to program the ladder logic, typically unique to its product, 2) Some PLC'S have several programming languages, with ladder logic being one of the easiest. Are you looking to design systems, or an understanding of how to install, startup and maintain , as these would be 2 different directions. I was a corporate trainer for PLC and other industrial control systems for over 10 years ,training electricians and engineers ,and happy to provide insight.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
You can buy a very basic small PLC from A-B, a Micro810, for under $100, and the software can be downloaded for free. It's only a few I/O but it makes for a great self-trainer and once you learn the A-B programming techniques, you can expand your knowledge from there fairly easily. A-B supplies roughly 45% of all of the PLCs used in North America, so learning their system makes you valuable wherever you go.
If you want to go overseas, then learn Siemens.
If you want to go overseas, then learn Siemens.
Eduardo_1995
Member
- Location
- bakersfield california
My local college has an automation degree and plc's is the heart. I loved the book i learned with. also has a CD with logixpro so u can practice your programming. 10/10 book.
ISBN 10: 1605259454
Programmable Logic Controllers: Hardware and Programming
Rabiee, Max
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RumRunner
Senior Member
- Location
- SCV Ca, USA
- Occupation
- Retired EE
I have a left over, never-used Mitsubishi Programmable Controller Model Melsef FX Series. This is one of those left over hardware during my active days (I'm retired) providing services for the aerospace industries. Machine shops around the LA area were heavily involved in providing parts and support for the space shuttle program at the time.
It did keep me busy servicing and programming numerically controlled machines all across the western states.
It has its manual written in five languages. Let me know if you are interested.
I hope this will help you in your hands-on PLC programming.
- Status