PLC for a beginner

[MFS Electrical]

Sorry for sounding like a dehngis but what exactly is a PLC?
I noticed Trend mentioned above I’ve done some work with their systems iq3 xcite and the 963 front end on BEMS is PLC just another term for that or am I barking up the wrong tree?

 

[Bobster]

Sorry for sounding like a dehngis but what exactly is a PLC?
I noticed Trend mentioned above I’ve done some work with their systems iq3 xcite and the 963 front end on BEMS is PLC just another term for that or am I barking up the wrong tree?

Yes, BMS systems use very basic PLCs. Usually with some form of telemetry unit so the system can be controlled locally.

A PLC (Programmable logic controller) is (simply put) a box, with inputs and outputs. The inputs go in, the logic insides then determines if an output turns on.

For instance if input 1 is on turn output 1 on.

 

[timbobelfast]

I’ve never used a PLC before but have found myself looking at a job which is going to put me onto that particular learning curve.
This is for lighting control, nothing to do with machinery or similar applications.
I’ve done a bit of research comparing features, price, availability, reviews etc and come to the conclusion that Siemens look like a pretty good bet. Does anyone here with experience in the field have advice? Are Siemens a popular unit or are they one to avoid?


I have looked at Siemens logo smart relays for other jobs and trialled them in demo software and found it to be pretty good but never actually got to using one.
I don’t think a smart relay will do this job as all the ones I’ve looked at don’t have enough I/O for what I need. At the moment I’m looking at 24 push button inputs and 48 outputs (based on the old, failing, system)

I have a stack of notes on PLC programming. Only ventured into the world of PLC last year. Took a Siemens course which was intense. Also use Mitsubishi FX and Q series. Prefer Mitsubishi to be honest! Software is expensive and Siemens is the more expensive of the two.

 

[Dave OCD]

I think in my case I'll continue to steer clear of this type of work.

 

[Kootni]

I have a stack of notes on PLC programming. Only ventured into the world of PLC last year. Took a Siemens course which was intense. Also use Mitsubishi FX and Q series. Prefer Mitsubishi to be honest! Software is expensive and Siemens is the more expensive of the two.

can you share the notes with us? email is: [email protected]; much appreciated.

 

[davesparks]

7 months on and the job is finally happening!

The first stage of the job has happened, the old control system is out and the new panel is in, I've got all the existing circuits working and returning next week to start the next stage of adding the new elements to the system.

I opted for the Siemens s7-1200 PLC and managed to get the hang of writing very basic ladder logic programs pretty quickly, or at least enough to get lights to come on when buttons are pressed.
And the bonus was that the program actually works!

I will update this thread as the job progresses and I'll try to get some pictures so you can all take the ----

 

[telectrix]

any useful info you can pass on regarding PLCs will be appreciated, digested then discarded. old dogs, new tricks etc. .

 

[timbobelfast]

Sounds promising, are you using TIA step 7 ?
What's the panel controlling?

 

[davesparks]

Sounds promising, are you using TIA step 7 ?
What's the panel controlling?

Yes, TIA portal step 7 which came bundled in the starter kit.

The panel is controlling lights. Specifically the backstage working lights in a theatre.

Control of these lights is via a master pushbutton station with some zones having their own local pushbutton stations. There is going to be a button at stage door to provide a last out / first in function. And also this system will incorporate 'grid beacons' which are flashing beacons to warn people of overhead work, this includes a sounder which will give a 3 second tone when the beacons are switched on and a different tone when they are switched off.

So it's very basic stuff as far as the PLC goes, but a good learning experience.

 

[gnuuser]

Sorry for sounding like a dehngis but what exactly is a PLC?
I noticed Trend mentioned above I’ve done some work with their systems iq3 xcite and the 963 front end on BEMS is PLC just another term for that or am I barking up the wrong tree?

a plc is a programmable logic controller ( as small real time automation control computer used in many pieces of industrial equipment such as conveyor systems, packaging equipment, or any process you want automated)
a plcc is a programmable logic controller computer! This is a dedicated computer permanently connected to a plc system to manage and program multiple networked plc, slc's and vfd controller banks found in motor control cabinets.

plc and slc systems use ladder logic programming and sometimes panel view for simple interface programming using block diagrams