Standard protocol for PC - PLC communications, manufacturing management

[flathead86 0]

Hi there all, I have a problem which I have to solve in a short time. There is a multifunction manufacturing machine (it feeds sealing material, then puts the upper housing on the lower one, then pressing it), which is programmed by me, the controller is an Omron CJ2M modular PLC. The machine have to do the following things (beside other things): - communicate with a PC, that communicates with the local MES (manufacturing execution system) through ethernet (this last thing is irrelevant for me) - my machine have to send the datamatrix code of the product to the PC (the PC looks up in the MES if the product is authorized for further production, eg. going through in my machine) - the PC sends back information about the product, if it is authorized for further production or not (eg. a YES or NO information) - my machine have to send information to the PC about the product, if it was: - passed through all of the three process steps (see above) without error - if there was an error during the process, and what was this error (sealing process or pressing process) - the final values of pressing force (KN), pressing route distance (mm), sealing material volume (ml) This all is not a problem for me, but there are other machines of mine, and I would like to use a standard protocol, to make this whole thing easier and uniform in the future, because the other machines have different communication "protocols" (things that me and the IT man made up), and this is getting something like a big mess. My exact question is, if there is a standard protocol for things similar to my project. I would like to use standard protocol, because it would be easier and less complex for me in the future. The communication hardware layer is RS232 now, but it can be ethernet also. PS: sorry for my bad english Thanks in advance for your replies

[BobB 58]

If you have lots of different items I would suggest looking at hardware protocol converters so you can use a common top layer. For example I use Ethernet IP to BACnet converters for BMS connection and then just program the mapping in the converter. Fieldserver have a large range of protocols that can be converted this way. Another option would be Red Lion as they have protocol converters as well.

[flathead86 0]

Thanks for your answer.

[flathead86 0]

I've found the solution! I think it's very useful, so I tell it: This is the OPC (OLE for process control). Shortly, the main thing is that you run an OPC server application on a PC which you want to communicate with, and the app communicates with the plc over ethernet or RS232 through a protocol which is supported by the PLC and the server app too (for example Host Link or FINS in the case of an Omron PLC). Memory segments of the PLC are shared via tags defined on the PC, and can be read or written by the server app. Then the server app can communicate with other apps on the PC (I'm lack of information about the PC programming side), for example with a VB app or with Excel. There are many OPC server apps by many companies, Omron has also got one, called CX-Server OPC, and there is another one I found useful, called Matrikon OPC server, which has got a downloadable 30 day trial version, the full version license is 600 EUR per PC, the support is very good. Some useful links about the OPC: http://en.wikipedia.org/wiki/OLE_for_process_control http://www.opcfoundation.org/Default.aspx http://www.matrikonopc.com/ And there is another possibility for the task that is cheaper: you write an application that communicates over a standard protocol that is supported by the PLC, for example Host Link or Modbus, etc.

[eastken 0]

Hi, Flathead Thank you for sharing your work and resources about OPC. I also need to send the datamatrix code of the product to the PC, how did you do that exactly?

[Crossbow 294]

OPC isn't really a standard protocol, it's a standard method for access. Each product will still have its own protocols. OPC has been the simplest way to get data from a PLC to a PC for 20 years. Just realize for each brand of PLC you need different drivers, there is not one standard language for all. An OPC like Kepware offers drivers for nearly everything on the planet.

[Marksman 0]

does OPC also requires license? thanks