Black Box MD1640A, MD1641A manual 141

APPENDIX A: Troubleshooting

•Your communications software settings may not match the physical port the modem is connected to. The serial cable may be plugged into the wrong connector—check your computer documentation to make sure. Or you may have selected a COM port in your software other than the one the modem is physically connected to—compare the settings in your software to the physical connection.

•If the modem is on, the cable is plugged into the correct port, the communications software is configured correctly, and you still don’t get an OK, the fault may be in the serial cable. Make sure it is firmly connected at both ends.

•Is this the first time you have used the cable? If so, it may not be correct. Check the cable description on the packaging to make sure the cable is the right one for your computer.

•Peripheral expansion cards, such as bus mouse and sound cards, may include a serial port pre-configured as COM1 or COM2. The extra serial port, or the card itself, may use the same COM port, memory address, or interrupt request (IRQ) as your communica- tions port. Be sure to disable any unused ports.

To look for address or IRQ conflicts if you use Windows 3.1x, select File, Run in Program Manager, type MSD, and press ENTER. Then select Mouse, COM Ports, and IRQ Status and note the addresses and IRQs that are in use. If you find an IRQ conflict, note which IRQs are not being used, then change one of the conflicting devices to use one of the unused IRQs. If you find an address conflict, change the address of one of the conflicting devices.

To change a port address or IRQ in Windows 3.1x, double-click the Control Panel icon, then the Ports icon. Click on the port you want to change, click Settings, click Advanced, and select the new port address and/or interrupt. If you wish to use COM3 or COM4, note that COM3 shares an IRQ with COM1, as does COM4 with COM2, so you should change their IRQs to unused ones, if possible.

If you use Windows 95, right-click on My Computer, select Proper- ties from the menu, click on the Device Manager tab, double-click on Ports, then double-click on the Communications Port your modem is connected to. In the port’s Properties sheet, click on the Resources tab to see the port’s Input/Output range and Interrupt Request. If another device is using the same address range or IRQ,

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