PC industrial control

I would like to know if there is any software out there that would allow me to use Ubuntu or any Linux distro to interface with I/O modules. By interfacing I mean to say I would like to be able to control say the starting of a motor, or the open/close state of valves. The programming I can do in any language supported by Linux distros, all I would like to know is if there is a program out there with an open source that I could modify at my leisure.

On a similar note, I am open to restrictions, such as, I am willing to receive input about examples of how others have interfaced with I/O modules via PC. It's best to follow others' examples as I'd be swimming charted waters right there.

Thank you in advance.

Yes. Lots. The most obvious is to connect to an I/O module over Ethernet.

Modbus/TCP is easiest. http://www.modbus.org Lots of I/O options including Wago, Aromat, Turck, etc.

EtherCAT is pretty cool. http://ethercatmaster.berlios.de There are fewer options for I/O, Beckhoff being your main choice.

I don't like Ethernet PowerLink (EPL) because it requires the use of hubs instead of switches, but at least they have an open source implementation. http://sourceforge.net/projects/openpowerlink B&R is the main I/O supplier, but Wago is also available.

There are other Ethernet modules, like Advantech's ADAM series, Elexol's Ether IO 24 R, Opto-22's SNAP I/O, etc.

You can use USB instead, with Advantech again, or National Instruments. You can even do Firewire with Wago.

There are PCI and even PCI Express plug-in cards. Advantech, National Instruments, Opto-22, and a host of others.

Virtually all of this stuff has Linux drivers, or documentation on how to implement in Linux. Essentially any language will work.

-James Ingraham
Sage Automation, Inc.

I have a project at: http://sourceforge.net/projects/mblogic/

Go to http://sourceforge.net/project/showfiles.php?group_id=228414 to find the latest release. Have a look at the project web pages for documentation.
http://mblogic.sourceforge.net/

This project has a number of packages including servers (slaves), clients (masters), and libraries which you can incorporate into your own custom
applications. It also includes a soft logic library which will let you run programs written in IL (Instruction List). This will (within a month or so) be incorporated into MBServer to make a complete stand alone soft logic system.

It presently supports Modbus/TCP and a Modbus-like web service as well. Modbus/TCP is a very common Ethernet based industrial protocol, and of the
major protocols is the only non-proprietary one.

All the packages are written in Python and developed on Linux (they will also run on MS Windows though, and probably Mac OS/X as well). MBServer also needs Twisted, but Twisted is in the standard Ubuntu repositories so you can install it with Synaptic with a couple of mouse clicks.

If you have any more questions, let me know and I will be happy to answer them.

Google Comedi, it will let you use a DAQ card from various sources to control things. The only problem is most cards have ttl level outputs. I designed and built a card to give you 24V levels from a commodity DIO48 card. But you can get drivers for some relay cards and I think I heard about drivers for Opto-22 racks also. If you want a soft PLC on Linux check out the MAT/PLC project.

Regards
cww

You might have a look at http://pvbrowser.org

It is a HMI/SCADA framework.

Supported protocols:
- Modbus (Serial Line and TCP)
- Siemens TCP
- Siemens PPI
- Ethernet_IP
- EIBnet/KNX
- OPC XML-DA
- PROFIBUS
- CAN

We are engaged in building an easy way to control a plant with a Linux PC, Modbus/TCP modules and python. We call it likindoy-RTU.

We'll be testing and documenting our likindoy-RTU in September. Follow our efforts or join us if you wish at the project's web site: http://www.likindoy.org