Hello Mr.Kunaal Lagwankar,

Your information was a big turn forward for me.Cause i was wondering if the PLC,IO cards & PC all are on the same modbus then how can the PC be master as PLC has to acquire data from the IO cards.Thanks a lot....for such a valuable info

Can you tell me whether PLC uses a serial or parallel communication with the IO cards.Because i mistakenly understood that all IO cards also are on the same modbus & i designed IO cards with serial RS485 link.Ofcourse i have one more serial port in the chip which i had thought of using it for MODEM interface but may be i have to use that for the PC now.Can you suggest me a web link where i can get more depth knowledge about internal hardware & software protocols of the PLC.Because i have never worked with any PLC but my client has but he is also NOT an expert at it.


Thanks,

Regards,

S.Sheik mohamed