FAQ - Data Acquisition Devices

What sampling rate can I reach with Quanser Q2-USB and Q8-USB data acquisition devices?

The Q2-USB and Q8-USB have 'Normal Mode' and 'Fast Mode' options that determine the max samping rate that can be reached.

  1. Fast Mode: The base communications rate is 125 us but the effective control rate is 4000 Hz. This mode is very intensive on the CPU and requires a higher end PC to reach the high control rates.
  2. Normal Mode: The base communications rate is 1 ms but the effective control rate is 500 Hz. This mode is not CPU intensive and will generally work well on most PCs.

The board specific options are on the main tab of the HIL Initialize block. There should be a “…” button to the right of the boards-specific options which will bring up a second dialog where you can switch between normal and fast modes.

Alternatively, change the board specific options directly on the text line from “update_rate=normal” to “update_rate=fast”. If the string isn’t currently in the list of options, then just append it to a list (options are separated by semicolons e.g. update_rate=fast;ext_int_polarity=0; etc). This image is an example of the Board-Specific Options window when Q8-USB DAQ is selected.

Do the Quanser Q2-USB and Q8-USB data acquisition devices have a fuse or protective circuit on them, like the earlier Quanser Q4 and Q8 Hardware-in-the-loop boards?

Yes, both the Q2-USB and Q8-USB have internal fuses but not replaceable as with the previous Q4/Q8 boards. These boards have a resettable fuse. Basically, if you exceed the current rating for the device, an on-board fuse will heat up, increase in resistance and prevent current flow. Once the circuit driving the excessive current is removed, the fuse will cool down and resume original low-resistance state. Thus you don't have to change the fuse.

Can I achieve 10 kHz sample rate (0.0001 sec sampling interval) with the Quanser Q2-USB or Q8-USB Boards?

The Q2-USB and Q8-USB data acquisition devices are not capable of reaching 10 kHz sample rate. The Q2-USB can only run at a maximum of 4 kHz given a very high end PC. The typical loopback latency to expect is 1 ms. For more details on sampling rates, please refer to the first FAQ item.

I just upgraded my system from Wincon to QUARC and I have a Quanser Q4/Q8 Hardware-in-the-loop board. Where can I obtain the drivers for my Q8 board, as well as instructions for their installation/setup?

All drivers for the WinCon supported Quanser DAQ devices, Q8 and Q4 are installed automatically when QUARC is installed. To test your DAQ with QUARC run the "QUARC Analog Loopback Demo". Type qc_show_demos in the MATLAB command window, scroll down and look for the "Using Hardware" demos group. When running this demo, make sure your DAQ has been selected in the HIL initialize block | Main tab | Board Type box.

How can I know if my Data Acquisition (DAQ) Device is supported by QUARC?

If you have QUARC installed, type qc_show_demos in the MATLAB command window.
On the left pane, contents tab, expand the QUARC Targets browsing tree.
Click on User's Guide.
Click on QUARC Data Acquisition Card Support.
Look for the card you are interested in and click on its name. Each card has a help page with complete information.

If QUARC has not been installed yet, check the Release Notes. Click on User's Guide, then click on QUARC Data Acquisition Card Support.

My Quanser QPID/QPIDe board was working fine but the encoders suddenly stopped reading. What could be causing the problem?

After a PC or laptop resumes from sleep mode, the encoders on certain DAQ devices stop working. Refer to Appendix C of your QUARC Installation Guide. It gives you instructions on how to change the default settings of the Power Management software on Windows 7 to prevent the system from sleeping. Go to Control Panel | Hardware and sound | Power Options | and click on "change when the computer sleeps". Set the "turn off the display" and "Put the computer to sleep" to "never".


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