General Technical Reference

11.SetCommTimeouts	ReadIntervalTimeout
	ReadTotalTimeoutMultiplier
	ReadTotalTimeoutConstant
	WriteTotalTimeoutMultiplier
	WriteTotalTimeoutConstant
12. HWFlowContrl()	dcb.fRtsControl=RTS_CONTROL_HANDSHAKE
13. ReadFile()

Question 1

Why does the port stop responding when I use a program to fast open/close the port? On the other hand, if I just do a normal port open/close, the port will stop responding after about 100 times. In a related problem, if I use the port on a dial-up network, the port will sometimes stop responding, or when I add a new modem under Windows XP, the port will be dead the first time I use the modem.

Answer 1

For all of these problems, simply unplug and then re-plug NPort 1220/1240 from the computer’s USb port.

Question 2

NPort 1220/1240 currently supports baud rates from 600 bps to 115200 bps. However, if I set an invalid baud rate, such as 300 bps, the driver does not return an error.

Answer 2

This problem stems from the fact that some Windows operating systems do not alert the user to the baud rate limits of connected devices.

Question 3

Why is it that when I use NPort 1220/1240 under Windows XP, the OS loading is sometimes around 45%?

Answer 3

This problem is a common characteristic that appears when using USB devices under Windows XP.

Question 4

When I install NPort 1220/1240 under Windows 2000/XP, the COM port number is assigned by which USB slot I use to connect to my computer. What happens if I change the USB slot?

Answer 4

The port number will change. Keep in mind that the port number is automatically assigned by the OS.

Question 5

Under Windows 2000, it seems that the more USB ports I install (e.g., close to 25 or 30 ports), the port throughput drops to around 1%. How do I get around this problem?

Answer 5

We recommend limiting to 16 ports the number of USB ports installed under Windows 2000.

Moxa Technologies NPort 1220, NPort 1240 user manual General Technical Reference, Question