Yes, that's what I have been finding. I know where to go if I want to capture mega-samples per second or more. Most industrial applications, even those involving turbine control or boiler control don't require sampling like that. A few hundred per second or so.... more than enough. In the Water and Natural Gas systems that I work with, nothing happens 'extremely fast'. Most of the PLCs I work with do input scanning in the tens of milliseconds per channel.
David Dudley
>>> "Dalesio, Leo `Bob`" <[email protected]> 09/05/06 3:05 PM >>>
It would be best to write the drivers for the Siemans PLCs first - then you can add in the IOCs to talk to them and not worry about your plant wiring and IO. Once that is demonstrated, you can start a pilot project to replace a little IO and see what you think. The IO from Hytec is probably the closest to industrial. Most VME is what I would call scientific IO - fast, high precision, low latency response.
-----Original Message-----
From: David Dudley [mailto:[email protected]]
Sent: Tuesday, September 05, 2006 12:58 PM
To: [email protected]
Subject: RE: Equipment Availability
Most of what I'm looking to update / replace are Siemens 505 PLC systems. I'm told I can create an executable program in 'C' or another language, that I can download into the device, but I don't have any documentation on that capability yet. Unfortunately, these things use a specialized Ethernet card that isn't directly addressable. I'm hoping to convert these things into a IOC directly, either using another Ethernet card, or using a PPP connection through one of the serial ports. The chassis holds VME sized cards, and uses the standard VME P1 connector bus, but I don't believe i'm going to be as lucky as being able to just put a VME processor card into them (I wish!).
I spent 3 or 4 days looking for I/O cards for VME or compactPCI, and have discovered that there are very few industrial I/O cards offered. Industrial cards are usually optically isolated, and directly handle 110VAC on inputs and outputs, and the analogs all handle 4-10ma current loops without converters. You can use a simple resistor for converting an input (technically considered a 'kludge' by most in industrial working circles), but analog outputs generally take special adapters to convert from voltage to current.
You can't normally run voltage I/O for hundreds of feet without interference from other signals in an industrial plant, but you usually can with current loops.
David Dudley
>>> "Dalesio, Leo `Bob`" <[email protected]> 09/05/06 2:15 PM
>>> >>>
You don't need to use VME though - you could just as well talk to PLCs from your Linux or Windows box. What kind of I/O do you have sitting around? We do a lot of RS232, GPIB, OPC, and many PLC manufacturers. Unfortunately, the web page is woefully underdeveloped for the IO that is supported.
Bob
-----Original Message-----
From: Steven Hartman [mailto:[email protected]]
Sent: Tuesday, September 05, 2006 11:51 AM
To: David Dudley
Cc: [email protected]
Subject: Re: Equipment Availability
On Tue, 5 Sep 2006, David Dudley wrote:
> who makes the chassis and backplane?
There are a large number of manufacturers, covering a large price range.
Take a look at VITA or the ads in VMEbus Systems magazine. Here are two I am familiar with:
http://tracewellsystems.com/
http://www.wiener-d.com/
--
Steve Hartman
[email protected] || 919-660-2650
Duke Free Electron Laser Laboratory
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