Pointers/advice for machine control elements

I am looking for help in selecting a cost effective PLC, IP67 operator interface and mobile broadband connection for a hydraulic press.

Initially I need to model/describe what is it that I need the machine to do. I have it in my head. Other than writing it down, describing the functions - I'm stuck. I'd like to use an industry standard representation. A FDS (Functional Design Spec)? Any pointers as to where to find a template for an automated machine would be helpful.

The machine will be a hydraulic press with hydraulic rams controlled via electro hydraulic solenoid valves switched by the PLC. Ideally 12V DC operation but if I have to go to 24V DC I will. Digital IO = 16 digital IO with room to expand to 32 IO and possibly 64 IO. Analog IO = 4.

For the PLC programming, Structured Text would be my preferred method although I can handle ladder logic. No idea as to program size as yet. If interfaces like USB are available e.g. for memory sticks that would be superb.

Operator interface will be flat panel, touch screen, IP67. Color possibly depending on cost. PLC and other electrical items will be housed in an IP67 enclosure.

Communications - local. I'd like to be able to interface a laptop to the PLC via a standard CAT 5 RJ24 ethernet cable ideally via a web browser.

Communications - remote. The machines will be used in fields (green grass type fields). I need the ability to be able to connect to them remotely via a mobile phone connection. Ideally mobile broadband (hundreds of kbps) but HSDA/GPRS (10's of kbps) at a minimum. I'm looking for a functional equivalent of www.logmein.com (LogMeIn Free) for the PLC world if such and annimal exists. I puzzled as to how to interface a standard mobile phone to a PLC.

I have a degree in Mechanical Engineering. I spent 7 years writing embedded control programs for Intel 8085 microprocessors and Intel 8051 microcontrollers using Assembler 80 and 51 and PL/M 80 and PL/M 51 (high level Pascal type languages) in the 1980's. My PLC exposure to data is from getting data from a PLC into SCADA systems for using in trending or data historian applications via DDE or OPC.

My searches to date have honed in the the Schneider Twido/Magellis or the Automation Direct PLC-05/C-More.

Looking forward to your replies,
Tom (in the Emerald Isle)

Try this! Has pretty much all you want in a single package.


http://www.heapg.com/literature/CutSheets/XLe_Brochure_final.pdf

and/or this

http://www.heapg.com/literature/CutSheets/XLseriesBrochure.pdf

That's a lot of questions for one post.

PLC choice - you will find quite a few threads covering peoples personal preference. For you to narrow things down you need to know what inputs and outputs you need both digital and analogue. That will then give you the range to consider, from cheap to 'ouch'. From your description of the project I would say you were at the cheap end of things. The only issue could be wanting to login to the PLC via ethernet that usually raises you a bit above cheap. Modern HMIs allow you to login to them via ethernet so it may better to let the HMI get the data from the PLC and then remote view the HMI. My choice for simple apps is the Siemens S7-200 range coupled with a Beijer HMI, Siemens have always had good support in the UK and Beijer HMIs are among the simpler to program. But ask anyone else here and you will get 100 different answers.

As for power supply, the industry standard is 24V d.c. you will limit your choices if you go for 12V and remember that if you are taking power from a battery the voltage will be 13.8 when it is being charged. Personally I use DC/DC converters to go from 12V to a stablised 24V but obviously it adds to the cost.

Remote comms are a lot easier than they used to be, Google for 'machine to machine' or 'M2M'. Your application is a little more complicated because you want to login to the machine from a remote computer. Have a look here for the basics.

You have some serious reading and studying to do, Good luck.

Bryan

Thanks Bryan and Bits and Bytes for your replies.