Running PLC Programm

RockyWells · Mar 30, 2020

Hi All, I am writing a piece of software for some research and would like to retrieve a running program from a PLC using python or some other available API.

I would be testing this on a MicroLogix AllenBradley shoebox PLC

Does anyone know what API or Library calls I could use to achieve this?

Is this in one of the Protocols like Modbus?

Thx!

Steve Bailey · Mar 30, 2020

I think you would need to launch the programming software and use it's upload/download utility. The ability to transfer the program is not included in the Modbus function codes.

RockyWells · Mar 30, 2020

Thanks Steve, I believe modbus may support this, the protocol suggests there is a read and write file operation.

The program file is supposed to be file 2 . I need to confirm this.

I want to be able to draw my own image from the ladder logic in the file.

paraffin power · Mar 30, 2020

You can't upload a program with Modbus. I assure you.
Steve's suggestion makes sense.

Maxkling · Mar 30, 2020

Are you talking about uploading the logic or reading the modbus registers?

RockyWells · Mar 30, 2020

I want to retrieve the current running program. This is why I thought a read file would work.

dmroeder · Mar 30, 2020

See if this will help you get closer to your goal:

https://sourceforge.net/projects/abdf1/

RockyWells · Mar 30, 2020

Thx - I was already scanning through with delight the pylogix

dmroeder · Mar 30, 2020

RockyWells said:
Thx - I was already scanning through with delight the pylogix

pylogix doesn't support MicroLogix.

dcam · Mar 30, 2020

You can buy a copy of RSLOGIX500 from your local Rexell dealer for around 150.00 dollars. I have never heard of using the comm protocol ModBus for a MicroLogix program download. But alas...I am mildly retarded at times. There are free options for students I believe. Hope this helps.

RockyWells · Mar 30, 2020

Yes I have a copy, I am looking to connect some advanced technology I am working on *** TOP SECRET *** to download running programs from PLC via API or some lib.

It is for some cloud analytics,so I want to have my own driver stack, it will all be driven from backend servers.

No Upload, just download as step 1.

Steve Bailey · Mar 30, 2020

I, for one, fail to see why you need the ladder logic in the PLC to perform any "cloud analytics". I can understand needing to read the data values, but not the underlying logic.

RET · Mar 30, 2020

Sounds like he’s trying to do some shady stuxnet stuff.

Ken Roach · Mar 31, 2020

In this context, a "file" is not something stored in a conventional filesystem. It's a section of application code memory. "Modbus files" are literally little 16-bit data memory registers used to exchange small amounts of data between controllers and supervisory systems.

In general, the functions used to upload (from the PLC to a PC/Server) or download (the other direction) are not documented, nor an API well supported, for use by third-party software. It's largely proprietary.

Doesn't mean you can't figure it out. And just because I can't think of a "cloud analytics" reason to read the application code of a MicroLogix doesn't mean there isn't one.

There is already a disaster recovery / automated archive / upload-and-compare product on the market, called FactoryTalk AssetCentre.

RockyWells · Mar 31, 2020

Thank-you for all the options, the source forge lib is probably the best place to look into. I was hoping there were some more public APIs for this or standard protocols I could implement.

Time to dig out the old protocol analyzers!

To the stuxnet guy, pssst buy more gold.

Running PLC Programm

RockyWells

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Steve Bailey

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RockyWells

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paraffin power

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Maxkling

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RockyWells

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dmroeder

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dmroeder

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dcam

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Steve Bailey

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RET

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Ken Roach

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