The difference of two simmilar USB 24 I/O MK3

2nd Board Arrival
The 2nd USB board ordered from Australia arrived today. It looks the same as the other previous one externally. So far the a few noticeable difference is the FTDI chip. This one is FTDI 245BL 612-1 while the previous one is FTDI245BL 607-1. While the new one a bit dusty the old one looks brand new. Next the sticker for new one is slanted while the old one nicely stamped.

IBM Thinkpad
The Windows 98SE has been fully installed as well as the Microsoft Visual Basic 6.0 Professional Edition. To make it nicer, the WinMac utility also has been installed. Now the Thinkpad looks like running Mac Os X server version. Next, the Borland Turbo C for DOS also has been installed as to test the old 8255 Program.

FTDI FT8U2XX Device Driver
The driver has been downloaded from the net. The are two options available. The firts is VLP and the other one is D2xx. The VCP driver emulates a standard PC serial port such that the USB device may be communicated with as a standard RS232 device. The D2XX driver allows direct access to a USB device via a DLL interface. As for our devices, I choose D2XX because our PC do have both USB and serial port. no need for emulation.

USB I/O 24 Test Utility
Download the test utility Visual Basic sample codes from elexol and compile using the VB6Pro under sample1 name. This is the putility rogram that I produce from the sample codes and use to test the two USB boards.



Test Result
As for board number 1 (hobby engr), when data 0 are written to Port A, Port B and Port C, then followed by reading them back, the answer are 0, 0 , 0. Even by running the continious testing with different input numbers, the values still 0 for all ports. ?
However for 2nd board, when 0 data were written, and followed by reading the port again, the data were 20H for Port A, 15H for Port B, and 0 for Port C. Even after reset all, when the procedures were repeated, the numbers read changed to different values. ?


Temporary Conclusion
I also confused which board is really OK, both OK or both NG. Further testing are arequired I guess!!!