Any favorite PC I/O for hobbiest?

Just wondering if there are any favorite I/O systems that are hobbyist friendly. Something like Ethernet I/O, ProfiBus, ModBus, DH+, RIO. For
example I know I can get an Allen Bradley PLC reasonable on eBay but then I need an expensive interface card, I just thought their could be a more economical way I'm not aware of.
I know many of the HMI's can be used with many different brands of PLC's so they evidently have drivers and hardware to communicate. I thought someone may have a good source for interface cards and drivers to work with I/O.
I'd like to play with writing PC software to do HMI and control functions.
Thanks!
RogerN
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Perhaps a PLC is not the best way to go. Except for Modbus, the other protocols get complex or are proprietary. Why not use a get development board from Rabbit Semiconductor, Microchip or Parallax?
If you do decide to stick with a PLC there are small MicroLogix plcs that can communicate with Modbus. Also the DL06 from automation direct is very cheap. I believe the DL06 can communicate using Modbus and Modbus/TCP if you by the Ethernet card.
Peter Nachtwey
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<snip> /Perhaps a PLC is not the best way to go. Except for Modbus, the other /protocols get complex or are proprietary. Why not use a get /development board from Rabbit Semiconductor, Microchip or Parallax? / /If you do decide to stick with a PLC there are small MicroLogix plcs /that can communicate with Modbus. Also the DL06 from automation /direct is very cheap. I believe the DL06 can communicate using Modbus /and Modbus/TCP if you by the Ethernet card. / /Peter Nachtwey
A few years back Mitsubishi was selling their old FX2n controls on eBay and I bought a few of those for the $35, $45, $55 range, came with software, I ordered a clone SC09 programming cable. I also have a Rabbit, Basic stamp 1, PICs, and Atmels AT Mega.
I kind of had in mind that Quikpanels, PowerPanels, and CTC touchscreens would connect to several different PLC's. Somehow these 3rd party panels obtained information on how to read and write to the different PLC's. I didn't know if the protocol information was freely available or if they buy the information (or drivers) from the manufacturers.
So I'm wondering if I can read/write information to/from, for example, my Mitsubishi PLC's using the programming cable and a program written in perhaps BASIC or C? I guess another possibility would be using AB's DF1 RS-232. My idea is to write a control program in the PLC and be able to adjust settings from the PC, or perhaps read the inputs and write the outputs directly from the PC.
RogerN
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Instead of PLC hardware, look at Bruce Chubb's C/MRI (Computer / Model Railroad Interface), http://www.jlcenterprises.net /. It uses an RS232 or RS485 serial interface with a simple protocol that supports up to 32 Kbytes of I/O on a single network. Although it's targeted to model railroaders, the hardware is general purpose 5 or 12 vdc discrete and 0-10vdc analog I/O. I'm using it to run 27 4-coil stepper motors on one project. The manual includes samples in QuickBasic and Visual Basic, but the necessary routines can be translated into any language.
Mike
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If cost is a factor, you might want to take a look at SPLat (google it). Compact single card controllers with a heap of I/O options including some with real industrial strength, and connectivity via Modbus. The hardware is way cheaper than PLCs, and all the software is free download.
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That looks pretty neat, I may order a development kit when my financial condition is a little better (we've been having curtailments at work).
RogerN
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I used to have a lot of success with the products like this from Advantech:
http://www.advantech.com/products/PCL-711S/mod_1-2MLHVN.aspx If you click on GET QUOTE it will pull up a price for you.
Plugs directly into PC bus - various types of interfaces available.
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Thanks for the replies all! It helps to know about some hardware I didn't even know existed.
In school people do learning projects such as the typical stoplights, etc.
I like to do home projects that are fun, educational, and it helps if they are somewhat useful too. Recently I connected a Fuji temperature control with ramp and soak. I've used it with a SSR to control the temperature of my Brinkman electric smoker. I can smoke a pork butt for pulled pork BBQ and not have the temperature shoot up if the water pan runs dry. Now I'm just using a thermocouple to keep the smoker temperature at 225 deg. F. In the future I'd like to use a probe and use ramp and soak to get the meat from cold to the cooking temperature (190F for pulled pork) in about 10-12 hrs and soak a little, then ramp down to maybe 140F keeping warm. The electric smoker does a good job with addition of some wood chunks for flavor.
The only problem with the Fuji temperature controls for smoking is that the ramp and soak doesn't wait on the meat to reach the setpoint (AFAIK), it just advances the setpoint over time, if the setpoint isn't reached, it doesn't wait. So, if I would use a PLC with with a thermocouple or RTD card, I could monitor the smoker temperature to keep it 225F and wait on the meat to reach done temperature, then turn on a "Done" indicator and allow the smoker to go to 140F (the safe keep warm temperature). Good BBQ from playing with controls!
I also use these Fuji controls (I got a lot of 11 on eBay) for temperature control on my electric radiator room heaters. They are great for keeping cold areas of the house comfortable, I don't have to overheat one room just to keep the bedrooms comfortable.
My other controls use in my home shop is I use EMC running in a Linux PC to control a CNC lathe. I get 3 phase conversion and spindle speed control from a VFD. I also have a CNC mill running off of an old control that I plan to upgrade to EMC in the future. With additional I/O I could automate part feeding, coolant and stuff like that.
RogerN
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