increasing communication distance

i am working on a project which features communication of my programming device(PC) with siemens plc.I have MPI adopter to make compatibility for my PC RS 232 with PLC.BUT the communication
in RS232 ranges for wire length of 20 meters. Thus Plc cannot be communicated at a distance more than 20 meters.I want to increase the distance to one kilometer.For that i have thought of Using RS485 converter to convert Rs232 to RS485 so that wire lenght can be increased and distance communication(point to point) between two units is possible(i.e PC with siemens plc).Now i want to ask whether it is feasible.if so can any body give Rs232 to Rs485 converter schematic which is easy to make,reliable,and workable so that it can be used on both ends.suggest some other easy and cost-effective ways to increase distance between two communication points. i hope my queries are clearly understood

I have used line drivers from Black Box for a similar project.

Hello Ravilal;

MPI is a RS-485 network, so it should access a node at 1 km at a speed of 9600 baud; for faster speeds you would need RS-485 repeaters. For MPI topologies, search for info on the Siemens support webpage (sorry, I don't have access to my files for the moment, so I can't be more specific).
One thing: the PC at one end of the link will probably need an integrated comm card (a CP5611 PCI interface will do) instead of the PC adapter, as this is powered from the PLC commector. Maybe someone who has more recent experience with MPI comnections can correct this if it is a wrong information.

Hope this helps,
Daniel Chartier

Hi

There is place where you can look at converters. They are cheap one, about 40USD. Actually there are schematic diagrams and I'm interested too...

If you will have really working ideas, please inform me too...

http://www.ipc2u.lt/catalog/0/cz.html

dchartier said:

MPI is a RS-485 network, so it should access a node at 1 km at a speed of 9600 baud; for faster speeds you would need RS-485 repeaters.

Click to expand...

That's interesting, I thought that the maximum cable length of MPI is 50 meters, then if you wish to go further than that you added repeaters, regardless of baud rate, up to a maximum distance of 1100m and 32 devices, including repeaters. The maximum distance between two repeaters can be 1km providing no devices are connected between the repeaters.

ravilal and others

I will repeat what Daniel stated MPI is RS-485, so you do not need a convertor.

Paul

Hi Ravilal,

This is something I downloaded some time back. Its not been tried by me. Try it and let me know.

Ron

Hello ravilal;

Maybe this document from Siemens can clarify my earlier statements:


Hope this helps,
Daniel Chartier