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how to read plc signal with external software?

how to read plc signal with external software?

(OP)
Hello,
I want to analyze data from grinding machines in my work place.
For that i have to read plc output variables like spindle load using programming language like c or dot net.
I know the variables names but i dont know how to access the plc to read.
The plc is made by the machine company, its not one of the known manufactures like Fanuc.
Is it possible to read the plc without the machine manufacture assistance?
Is there any external free software that can do it?

RE: how to read plc signal with external software?

That is a very loosely formulated question. Practically impossible to answer.

We have assisted a grinding expert, one of the top ten in the world I think - PHD and all, in analysing crankshaft grinding for a dominating truck/bus manufacturer. So there was a lot of expertise available and the CNC manufacturer was willing to help. Even then, it was easier to apply an external power transducer plus a few more transducers for speed and such things and collect data in an external logger. We used CSV and data were later transferred to Excel/Matlab etcetera for analysis and presentation.

Our first application was for a small pump. The results were so good that we later used the same technique for the grinding tets. The pump application can be found by googling "Power measurement using analogue Power Transducer on PWM"

Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

RE: how to read plc signal with external software?

I doubt that you will be able to read anything without help from the manufacturer. As a minimum you will need to know what protocol(s) the grinder controller can communicate to.
As an alternative you could add some devices to allow you to collect some of what you want. By putting Amperage meters on the motors and an encoder on the spindles you could add your own ability to monitor but not control speed and load data on the wheels.

RE: how to read plc signal with external software?

(OP)
The machine's pc is running in windows environment, is there any more information i can extract with windows tools or external software that can assist me?

RE: how to read plc signal with external software?

How is the PC connected? RS232? RS425? USB? There are protocol analyzers that can listen to the data. It may be possible to extract useful information from the data stream. No guarantee, but worth a try. Perhaps "the kid next door" has an idea?

Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

RE: how to read plc signal with external software?

Beyond just getting to the data, you still need the manufacturer's documentation on what the data means. I've seen systems where 3 output variables are all encoded into a couple of bytes, which requires you to know which bits go with which variable.

TTFN
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Of course I can. I can do anything. I can do absolutely anything. I'm an expert!
There is a homework forum hosted by engineering.com: http://www.engineering.com/AskForum/aff/32.aspx

RE: how to read plc signal with external software?

You'll waste your time trying to use existing data, you're not sure whether it's a PC or a PLC and have no help from the vendor.

You need take dV8r's advice and add the sensors you need, use some data acquisition to collect the data and put it in a database and then do whatever analysis in whatever programming language you're familiar with .

Look up National Instrument. They have PC based I/O and their software, Labview is widely used for this sort of thing.

RE: how to read plc signal with external software?

(OP)
IRstuff-
i have documentation, i mentioned it in the opening post, i know plc variables and meaning.

Skogsgurra-
i will check this, thank you.

danw2-
the software interface is running on windows platform, its not instead of the plc.

thank you.

RE: how to read plc signal with external software?

You might check out the C-More user interface panels. They're very easy to use and VERY effective. They're made to interface with a lot of different PLC families. I use them all the time and they're pretty painless. I use them directly for variable displays and HMIs. If you want to get data out from them I believe there are many models that will do that various ways for you included via the internet if that floats your boat.

You get free sw that is very clear to use and allows you enter variables living in the PLC and the C-More will continually fish them out of the PLC for display or export without any PLC intervention.

http://www.automationdirect.com/adc/Shopping/Catalog/Operator_Interfaces

Keith Cress
kcress - http://www.flaminsystems.com

RE: how to read plc signal with external software?

Wow! And Wow2! Keith.

I knew nothing about this. I'm not surprised that Keith turned out to be the "kid next door"! PLS

Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

RE: how to read plc signal with external software?

(OP)
I found the machine cnc device, maybe this could help.
Link

RE: how to read plc signal with external software?

That's not a PLC in the conventional sense where something like Keith's suggestion might work, it's a Windows PC running some sort of proprietary "Soft PLC" software in the background, probably to handle I/O functions via EtherCAT and communicate to the servos though a Sercos interface. Usually when a company like that uses their own proprietary platform and provides no information as to what it is, they do so because they do NOT want users accessing their IP for using it without their input, which generally involves paying for their help.


"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington

RE: how to read plc signal with external software?

AviSprngr -

i know that there are some drivers available that you can use to get data from the machine to the computer and analyse it. Depends what the machines are. and what data you are looking for.

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