RF-2296, RF-2064, RF-22192, PQN-560, ORG-560, All SDK Models, All RFS models

Why can’t my device communicate with my PC?
You may have an IRQ conflict with your serial mouse, an internal modem, and your device. 

IRQ's are the gateways to your micro processor, each communications port uses an IRQ.  Microsoft in their configuration allows Windows to label up to four Com(serial) ports even if you have only two Com ports physically present in the computer. Most computers come with only two Com ports. Each Com port uses a UART 16550 chip that is configured to only one IRQ.

There are two types of mice. You can tell which type of mouse you have by the plug that fits into the computer. A serial mouse will have a trapezoid 9 pin connector like the cable connector. The other style mouse, P/S 2 style, has a round connector with five pins.

If your mouse is a serial mouse it will most likely be on Com 1 and use IRQ 4, plugging the device into the open 9 pin serial port will use Com 3. Com 3 uses IRQ 4 because it does not have its own UART chip configured to one of the other IRQ’s. It will try to use the UART that the mouse is connected to, thus the conflict.  The mouse demands access to IRQ 4 all the time, and denies the software access. 

Meanwhile the internal modem is connected to the mother board and is on Com 2. Com 2 uses IRQ 3 (and its UART chip). The mouse and the modem are devices that demand full time gateways into the processor and thus capture their IRQ's continuously. Even with an open plug at the rear of the computer there is no IRQ for the device to use.

The solution to this IRQ conflict is to add a Serial Port board to the computer that can be configured to an IRQ other than 3 or 4.

You will need to use Win 95 Device Manager to find which IRQ's are open, in many systems IRQ 5, 7, 10, 11, or 12 will be available. With this information you will be able to purchase a Serial Port board that will allow configuration to one of your open IRQ's.

How do I know if my COM (serial) port is functioning properly?
Follow these steps to use HyperTerminal to test your COM port:

• Go to Start | Programs | Accessories.

• Double-click on the icon labeled Hypertrm.exe.

• When the program opens, configure it to connect direct to COM1, or direct to the COM port in question.

• After you select OK, select OK for the COM port parameters. You should then see the CONNECTED message in the lower left hand corner of the HyperTerminal window and a counter counting up in one second intervals. 

• If you receive an error message such as Unable to open COM1, you should consult the manufacturer of your computer to solve your COM port issue.