Freeing All DMA Channels from an AT E Series Device

If you want your AT E Series device to use interrupts only, although the device has DMA channels allocated to it, call the NI-DAQ function Set_DAQ_Device_Info (or the LabVIEW Set DAQ Device Information VI) and change the transfer mode to Interrupts Only. Alternately, you can use the Device Manager to remove all the DMA channels allocated to an AT E Series device. Follow these steps to free DMA channels in Windows 2000/XP:

1. In Windows 2000/XP, open the Device Manager by going to Start»Settings»Control Panel»System. In the System Properties window, select the Hardware tab. Click Device Manager.
2. Expand Data Acquisition Devices to see a list of installed DAQ devices. You will see two entries for each AT E Series device, distinguished by the suffix Logical Device (1 of 2) and Logical Device (2 of 2). This is due to a Plug and Play limitation.
3. Select the first logical device, and click Properties. In the Device Properties window, select the Resources tab. Next to the field labeled "Setting based on," select basic configuration 0002 or 0003 for the first logical device to take away both of its DMA channels.
4. To remove the DMA channel assigned to the second logical device, deselect the second logical device under the Device Usage section in the lower left-hand corner of the General tab. Restart your computer.
5. The next time you run MAX, you should see no DMA channels associated with your device. If this does not work (even though the second logical device is disabled, Windows 2000/XP sometimes reports that it has a DMA channel allocated to it), try one of the following two approaches:
   • The easiest approach is to reserve resources in the Computer Properties page for your computer. Access this by right-clicking the Computer icon in the Device Manager and selecting Properties. When the Computer Properties box opens, select the Direct Memory Access (DMA) option and then the Reserve Resources tab. If you have an ISA bus computer and do not want an AT E Series device to be assigned any DMA resources, reserve any of the channels 5, 6, and 7 that are not already in use by some other device.
   • Another approach is to make sure that other devices are assigned all of your available DMA channels before your AT E Series device. If you have other hardware that needs DMA channels, you can install that hardware first. If your AT E Series device has already been installed, you can remove it from the Device Manager and refresh again after your other hardware has been added.

If you have an AT E Series device and an EISA bus computer, refer to EISA Bus Computers.