calvin

It's possible to use a second COM port for communications spy, I did that with VisualBasic, but is much easier with a software like this http://www.aggsoft.com/serial-port-monitor/

Well the hard work will be how to send/receive data and not what to do with it But there it is an small example. PC Program: Send command button state to serial port (ON/OFF), with end message code (0A0D) Receive a message with a boolean variable and attribute its value to a checkbox (Lamp) On PLC program: send Y0 to PC, for monitorization receive command button order (ON/OFF) and attribute to M0 Y0=M0 or X0 P. S. In my opinion, checkbox are better than command buttons for this situation, you want that the same button set and reset M0, so you must change the caption to display the correct action.

hi neildobson Good job decoding the MC protocol, it look's a great VB application. Unfortunately i wasn't able to put it working I tried with a A1S PLC (communication Port), result: "RCV: Error no response from PLC!!" With a FX2N (communication Port),: "RCV: Unknown response from PLC!!" Unfortunately i don't have a 232-BD interface, but i think that the MC protocol also work on the Communication port. Can you tell if this is the protocol used by Mistubishi aplications to comunicate with the PLC, like GX developer??

I’m not sure of what you really want! You want to control the lamp (Y0) with a switch (X0) or with a Command button in Visual Basic. On the PLC side, the serial communication is based in integers (D’s), but you can convert to boolean, see my example. I forgot to say but the code is made on GX IEC Developer 5.0.

Unfortunately i don't have an FX232-BD. The only 232 module available is a A1SJ71UC24-R2 with a A1S CPU. In this example the left checkbox controls Y10, the right checkbox monitorize X0. The plc code is only for serial communication, there isn't any relation between X0 and Y10. For the FX series is available a RS function for a easier control of serial communications. Hope this help Serial_sample.zip

hi joven Like panic said, MX component is commercial so you need to buy it, same for OPC server. Back to the basic solution, develop a Visual Basic Aplication! I thing that the VB aplication is simple, but the PLC program can be a litle harder. To use serial communication on Visual Basic you need the MScomm object: Menu, Project->Components->Microsft Comm Control 6.0 I leave an very basic example, for tests use the windows hyperterminal that is even easier. For the PLC program, see the RS function (FNC 80) on the manual.

Hi There are several ways to make this connection, do you use the comunication port or and communication module?? Visual Basic 6.0 or .NET?

Chalpa is probably right If you are using a serial card (A1SJ71UC24-R2), is much easier to program a VB application with simple ASCII messages. The only problem is that in this case, you need to program the PLC to receive/send messages, see the R2 manual for an example.

What system are you using, ActiveX, OPC???? In the first post, appears that you want to write a new program, but seems that already have one Please explain better.

Hi If you are using the programming port of the PLC, is very likely that the visual basic application uses an Mitsubishi software for the communication protocols, presumable an ActiveX or OPC server, in any of this its necessary to setup the program with the PLC information, if you are using diferent PLC's thats probably the problem. Try see if there is any Mitsubishi software installed on that PC! ActiveX an OPC gives direct acess to PLC address memory, so in order to use the same Visual Basic application, need ti use the same memory address in both PLC's.

Hi A good way is an ActiveX control just like liuzu2000 say, the ActiveX Mitsubishi software is "MX Components". But perhaps an OPC server is better, Mitsubishi OPC server is "MX OPC Server", there are others OPC server with drivers for many PLC's including Mitsubishi, like http://www.kepware.com/ OPC is more robust, and easy to configure, but is a litte slower and hard to program... There are also an DDE server (Meldde), but nobody still uses DDE.

Thanks for the explication Crossbow So this MC Protocol, is the protocol used by all Mitsu applications, like Meldde, MX components, MX OPC and GX Developer! Maybe its possible to develop a PC aplication to send a new program to the PLC, based on the MC Protocol?

Thanks mjrx And for A1S?

Hi This protocol is only for Q series, or still work with FX and A1S??

hi What PLC do you have? Do you whant to know more about every M variables, maybe tou can be more specific...