Help on furthering my PLC knowledge.

[netblindpaul]

HMI = Human Machine Interface (Touchscreen)

dkent,
Not ALWAYS touch screen but the mnemonic is correct!

(Ex-PLC & CNC manuf. service engineer & Ex-CNC machine tool service engineer, we had our own control systems!)

 

[Knobhead]

HMI are the visual display units. Allow an operator to alter programmes, setting, dwell times etc.

Tony what plc's would the Modsoft software be compatable with? he programmes which i look at via RS logix/Rs linx etc are usually in ladder form and are easy to follow if you know what your are looking for.

Did you self teach or do some sort of training?

Mike

I got in to programming purely by accident. The plant I was working on was one of the first in the UK to use PLC’s. They were Modicon 284’s, a few months after I joined them the PLC’s were upgraded to 984’s, unfortunately the company wouldn’t pay for new I/O racks or having the programs re-written. At least we got Modsoft instead of dedicated programming panels. We finished up with an absolute ******* of a system. One program controlled a transport system, it would loose where it had put things, lock up and refuse to do anything. The only way to get it going again was to re-load the program. This happened while I was on nights and one of the directors had dropped in for one his surprise visits. He wasn’t happy, I wasn’t happy and we argued, me saying, “this is why we want to reprogram it”. “You’d better get on with it then”. Ooopps, Tony trying to extract size 10 boot from size 8 mouth. I’ll give the company it’s due, they let me get on with it. After that I did mainly modifications.

PL7 came on to site due to management interference. I wanted to use a Mitsubishi PLC but was shouted down and told to use Modicon because everyone on site understands Modsoft, pity the Modicon TSX used PL7 instead. So we ended up with a PLC that cost 6 times more than my original idea and no one had a clue how to program. It was purely trial and error getting the system working.

Have a look at http://www.barn.org/FILES/historyofplc.html

 

[netblindpaul]

Tony,
Your link mentions one of my previous employers!
The one where the guys dropped all the kit on the floor.
I spent 10 years working for them in various roles, most of it on field service.
One of the resons that Dick was unsuccessful was the tie up with Cranfield Uni in the UK where by Landis developed their own combined CNC & PLC control for the EU & American markets with their own funcitonality.
Though we did use Siemens, Fanuc & NUM also.
The PLC is only part of the automation story though is it not?

 

[Knobhead]

Some of the plants I worked on had some weird and wonderful control. One controlling a kiln was a 1960’s Feranti Argus 1000 computer complete with punch tapes and Teletype desk. It fell out of favour when it turned the fuel to full and closed the exhaust damper.

Other plants used hard-wired logic Solicon being the first followed by Logicon 1 and then Logicon 2. Rack after rack of individual logic units. In a way better than the PLC, logic was solved in real time and not governed by scan cycle. An absolute swine if you had to make any alterations!

Our first venture with PLC’s was with Texas Instruments, not a great success due to the scan cycle and reliability but we got around it. These were followed much later with Mitsubishi, they be came the standard on the works.

 

[Steve1412]

Local colleges usually run decent courses using mitsi FX or Allen Bradley SLCs they are reasonably cheap...If you go for manufacturer specific courses expect to pay £250 a day at least. The basic principles are the same in ladder logic but different software handles things in different ways.

 

[Knobhead]

I found that manufacturers courses tend to concentrate too much on configuration and topology. 9 times out of 10 you will find yourself with a pre-configured / installed unit. You don’t need to know how to configure them, just how to fault find. The last PL7 course I went on was useless because of that, so bad that half of us were ready to walk out.
I ended up running one to one sessions with the electricians just on the programs we had. It was fun for me going in and sabotaging the plant and then let them find what I’d done.
It was how I was taught by a French engineer that came to commission a new plant. He laughed as I blundered about at first.
My boss also French, came out with a comment / bet that I couldn’t write a deceleration algorithm for Modsoft. It should have cost him a steak dinner, rotten sod cleared off to another works before I could eat it.

 

[sbrown2]

I would generally agree with that sentiment. But I've worked on controllers where you have to connect to peripherals i.e HMi, interface to servo's, displays, networking and also sometimes you cannot restore a program without an amount of configuration of the connectivity settings. I would therefore say that although some say this is the boring part of training in plants with networks and many different controllers this could/is be invaluable. Its the same as apprentice training get the fundamentals correct. Not that thats always the case!!!!!!!

 

[Knobhead]

Trying to get faultfinding skills on a 3-day course when 2 of them are wasted on irrelevant rubbish spoils things. I learnt to configure Modicon 984’s and TSX as and when I needed to.

In fact I had to show one instructor how to get in to the configuration setup!

 

[Mike F]

Thanks for all your replies, i'm in chelmsford so any people who could help locally would be great. Today i spoke to Mark Gutteridge from Rockwell Automation based in dartford.

He is going to look into providing with some course information and possibly some good contacts of his. Also spoke to our production engineering manager at work today and he is prepared to pay for any formal training i require.

Had a good look at work today in panels which i have never looked in before and our site has one modicon PLC which is ancient. A few Siemens S5/S7 in some of the labelling line but i would say 90% are Allen bradley, whiich i commonly fault find and also noticed they are being used in more of the newer kit the company have bought.

Once again thanks for the replies.

Mike

 

[Knobhead]

Had a good look at work today in panels which i have never looked in before and our site has one modicon PLC which is ancient. A few Siemens S5/S7 in some of the labelling line but i would say 90% are Allen bradley, whiich i commonly fault find and also noticed they are being used in more of the newer kit the company have bought.

What model of Modicon?

 

[sbrown2]

The rockwell courses are very good. I did a advanced course and then arranged a specific DH485 networking course and they have served me well in relation to many other PLCs