Comm. Error With S7 200 CPU 224 via PC/PPI (USB) Cable

[pranav.mistry003]

Hi you all respected PLC Lovers,
I am new with the Siemens MicroPLC Family. I have one S7 200 (CPU 224) installed in one panel 5 or 6 years ago. I want to upload the Ladder Program from the CPU 224 to my notebook. But I am facing the communication error with the PC/PPI (USB) Cable. The plc is working fine in the run mode.

My notebook is having the following configuration...
- Operating System Win 7 Ultimate (I have installed Step-7 Micro/Win 4.0 sp5 along with v1.0 PC Access sp2 in the Win XP Virtual mode by VMWare Software)
- PC/PPI (USB) cable No. 6ES7 901-3DB30-0XA0
- I m not having a serial com port in my notebook

I have tried as following...
- Configured PG/PPI interface in the micro/win for USB cable.
- Tried the PLC to access in both Terminal and Run modes.
- When I connect the cable between PLC and my notebook 3 leds of PC/PPI Cable(Tx, Rx, PPI) instantly glows and then for 2 times Tx and Rx Leds glows.
- When I double click to refresh the communication, none of a single LED glows on the Cable

Where I am doing a mistake I don't know..
Please Help me... Await a favorable reply from you all....
Thank you so much..

 

[pranav.mistry003]

Hay I got the solution...
I successfully established the communication to PLC with my notebook..
I was missing some settings for Receive and Transmit Buffer of COM port.
(Look up: Device Manager > Ports COM & LPT > Communication Port (COM1) > "Port Setting" Tab > "Advanced.." Button > Rx and Tx Buffer settings
I set the Receive Buffer and Transmit Buffer to lowest value at 1 (Lower settings to Correct Connection Problems) and bingoooo.... I have made it..
But Can anybody tell me why this setting is required for USB port that I am using..?? I am confused about that. Please help me to know..