LabVIEW Real-Time and USB Frequently Asked Questions (FAQ)
Hardware: PXI/CompactPCI>>Controllers
Problem: I want to use USB connectivity as part of my LabVIEW Real-Time Application. Are there any caveats or limitations I should be aware of?
Solution: The following is a list of frequently asked questions (FAQs) regarding the use of USB devices with LabVIEW Real-Time.
1.Does LabVIEW Real-Time support USB connectivity?
As of LabVIEW Real-Time 8.6, UHCI (low-speed) and EHCI (high-speed) USB devices such as thumb drivers and external USB hard drives are supported for real-time targets with onboard USB hardware. OHCI USB devices are not supported.
LabVIEW Real-Time 8.0 and earlier does not support any USB drives. |
2. Can you hot-swap USB drives?
A USB drive is hot-swappable, and there is no special command needed to remove the drive before pulling it out. The USB drive must not be removed while a file read/write operation is in progress. Most USB drives have an LED to warn that it is in use, but as a precaution Real-Time code can be implemented to notify if a write/read is in progress via a flashing LED. Due to the nature of USB communication, it can take upto 5 seconds after sending data to the USB for it to be flushed from chace to disk, so this extra time needs to be taken into account.
When a USB drive is removed, and a new one is connected to the same USB port, the new drive will get the same drive letter as the old drive. |
3. Can you have more than one USB drive at once?
| Yes, each USB drive will have a different letter (D:, E:, F:, etc.) |
4. Can you remove the internal drive of a real-time system and only use an external USB drive?
| This is still not possible as of LabVIEW Real-Time 8.6.1. |
5. Can I use my USB DAQ device with LabVIEW Real-Time?
| As of NI-DAQmx 8.9 and LabVIEW Real-Time 8.6.1 (and prior versions), USB DAQ devices are not supported for real-time targets. |
Related Links: Product Manuals: LabVIEW Real-Time Module Release and Upgrade NotesKnowledgeBase 3YQ8O7TQ: Can I Boot into or Run LabVIEW Real-Time Using a USB Flash Drive?KnowledgeBase 39NDI8PK: Requirements for a Desktop PC as a Real-Time TargetKnowledgeBase 2KM92E5F: Using FTP to Access and Use the External CompactFlash or USB Drive on a Real-Time Controller
Attachments:
Report Date: 08/23/2006
Last Updated: 05/27/2009
Document ID: 40MDORS9
