Troubleshooting - AT RS-232 or AT RS-485 Windows 98/95

The following procedure is a standard means of isolating and solving serial problems:

Make sure the IRQ the serial port is using is not being used by another device. To free an interrupt request level for the serial port, you must disable a device that is using an interrupt request level. To view the system-wide allocation of interrupt request resources and remove a device, perform the following steps:
- Select Start»Settings»Control Panel.
- Double-click on the System icon.
- Select the Device Manager tab.
- Double-click on the Computer icon at the top of the Device Manager list of devices.
- Click on the View Resources tab.
- Select the Interrupt Request (IRQ) button. By scanning through the list of interrupt request settings, you can determine which devices are using which interrupt request levels.
- When you have located a device which you are not currently using, click Cancel to exit the Computer Properties window.
- Double-click on the icon for the device in the Device Manager list of devices. In the Device usage field at the bottom of the General page, a checkmark appears to the left of the current configuration, usually Original Configuration (Current).
- Click on the checkbox to remove the checkmark.
- Make sure that Use automatic settings is unchecked on the Resources page, then click on OK.
- Restart Windows 95 so it can correctly assign resources to the serial port. Then run the verification test.
Make sure the resources the port is requesting are available. When the resources shown under the Device Manager indicate a conflict with another device, you can often correct the problem by manually selecting conflict-free resources. Follow these steps to manually change the resources of an NI serial port.
1. Select Start»Settings»Control Panel.
2. Double-click on the System icon.
3. Select the Device Manager tab, and click the View devices by type button at the top of the page.
4. Double-click the Ports (COM & LPT) icon. A list of installed ports appears.
5. Double-click on the name of the serial port you want to change, then click on the Resources tab.
  
  Note: To change the resources of ports on shared IRQ AT boards from within the Device Manager, you must open the Multi-function adapters class and double-click on the name of your interface. Use the Resources page to change the resources. Any resource changes are automatically reflected to the child devices.
6. Uncheck the Use automatic settings checkbox and click on the Change Setting button. If the system does not allow you to change settings, select the configuration that gives you a conflict-free base I/O address and interrupt level from the Setting based on: list box.
7. Click on OK to close the Device Manager. Your conflict problem should be solved.