Hello,
I am new to this forum. We use Serial port and MSCOMM32 to communicate with our hardware modules which in general controls D.C. servo motors and collect data from sensors. The software is written in VB6 and all the DLLs are written in-house. I wanted to change the serial port with USB interface so i designed USB to serial module using FTDIs chip and using VCP drivers from FTDI. The module worked fine in my lab but at Customer's site it would give communication error or would stop communicating in between giving Error 8021. I updated the hardware driver but still could not find a solution.
My question what is the best solution to change the legacy Serial communication with USB interface. If needed i am ready to write whole new software but am looking for any starting point.
I hope i explained the problem clearly. Any advice is appreciated, Thank you.