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Gan Uesli Starling

Allen Bradley PLCs

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I am assigned to refurbish an airflow instrument having six pressure sensors, four temp sensors, and six on/off outputs. By preference I would use all NI hardware, but this isn't going to be allowed. I'm being pushed toward installing an Allen Bradley PLC instead. I am aware of another, much more complicated liquid flow test stand which, so I'm informed, uses LabVIEW for SCADA on a Seimens PLC. This being the case, cannot I do likewise with Allen Bradley? Can I do it entirely in LabVIEW? Or is something like that always just LabVIEW sending trigger commands and receiving data from a free-standing program written in the PLC's own native SCADA?

I'll be starting from scratch, with nothing yet purchased. I can purchase whatever I choose. I have perused a couple of PDFs of Allen Bradley ControlLogix programs, and at first glance, to me they look like a major pain. Unlike LabVIEW, almost nothing shows on any one screen. Nothing at all looked to have been nested into a subroutine. I liked ladder and highway diagrams quite well enough back in the 90's when printed out on D-size vellum. Then, at least, I could stand back and see the whole thing. The same thing seen only through a tiny window that you have to scroll up and down I'm not looking forward to learning at all. Thus my hope for a LabVIEW solution, rather than purchase and learn AB's Studio 5000. I'm an old dog, and this looks like a new trick to me.

Edited by Gan Uesli Starling
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I'm throwing in my all the way incomplete point of view, because my current project is a SCADA too, and I decided to go the labview way. However, I'm still asking myself about the rationale of my decision, and about the option of integrating PLCs at a later stage. At the design phase I looked at some docs of a few PLC vendors and their control software, and was scared off by their license tems (LV we have academic), by the learning curve and by the apparent (to me) clunkiness. Add to that that I presume that the bonanza I can get from the LV community largely surpasses the support, even paid, which I could get from a solid SCADA vendor.

It seems you are still deciding whether you need PLCs or not. If you're excluding NI (realtime standalone?) hardware, does it mean that you can afford the increased instability risk of running your business logic on a desktop computer? Is safety among your requirements?

(No connection with the particular vendor), I ended up purchasing a number of these Advantech ADAM-5000 modules, which seems a decent compromise for my needs. On one side, they are ruggetized and modular remote IOs, which I can easily read as modbus registers. On another, they seem to have a minimal capacity for an embedded logic (e.g. you can define logic functions of three inputs which are routed to another register of the same or of another module), thus potentially overlapping with minimal PLC capabilities. I'm currently testing them. Has anyone else used them and would share opinions?

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It's a political thing. In my own department (Test Engineering) we are fully invested with LabVIEW. The test stand in question, however, belongs to another department. And they are devoutly enamored of Allen Bradley. Cost is no issue, my company has full, all-encompassing corporate licenses for both NI and AB softwares. I am considered something of the plant-wide hardware and software guru, if only because I've been here 12 years. But this project got handed to me already with the AB constraint. Bit of an uphill slog in my future, so it would seem: new hardware & a new authoring platform.

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In general I am however interested in hearing about experiences and opinions about LV vs. X for building SCADAs. A quite broad question I understand, and much dependent on plant size and boundary requirements, but still.

In my case some of the arguments which drove me once more to LV were: heterogeneity of the hardware to be controlled, need to interface with other systems, perception of a higher freedom and power in concocting the HMI, academic rather than industrial work culture, presumption of insurmountable learning curves and additional license costs.

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Might be a case for a AB Micrologix.  These interface nicely with LabVIEW. 

Last time I used one, it was still good old ladders.  :) 

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