Open Source Softwares for Siemens S7-200?

Hi, I am a Student at University of Sheffield and I need to know if Siemens S7-200 PLC can be Programmed and monitored using an open source HMI software.

If configuring is not possible then is it possible to program it with Siemens MicroWin software and later use an Open source software to acces the PLC registers and use it for HMI monitoring?

I am designing a control system for a Micro Hydro Plant and I have to keep the cost down. Saving on the software will help significantly.

I will appreciate your reply...
Atif

Yes there is an open source driver called libnodave that allows you to connect to S7 plcs and read registers. You will have to write a program in VB or C to do so, libnodave will take care of reading and writing data from the plc.

you can read about it at http://libnodave.sourceforge.net

S7-200 serial port can also be used in freeport mode. There are some Modbus routines available for the S7-200, It may be easier to communicate with the HMI in this way.

Down side: If you only have a single port CPU then you cannot monitor the program whilst the HMI is connected. This makes debugging harder.

I have also looked at the libnodave libary, it works, but it is not (or wasnt a while ago) a fully developed dll, so there would be a bit of work to integrate it into an application.

Remember that the S7 serial port is RS-485

Thanx Rohan and Mike, the open source Libnodave definitly seems to be promising though it doesnt mention compatibility with S7-200, but I think it might work, will try it out.
Thanx lot. Will get back to you if I am stuck...
Atif

Its say PPI, thats the comm. protocol for S7 200. Its far easier to use OPC to do this but since you are doing it out of an academic interest, I would recommend libnodave.

I have a s7 200 plc version 1.12. It is password protected. But i need to program a HMI for the machine. Is it possible to read the program/ data registor which are used in PLC. If Yes please tell me how? Someone tell me that they can find the password of S7 200 PLC Version: under 2.1
Is it True? and they tell me their system is debugging.