how to increase DIO update speed of USB device

[BjornDeb]

Dear all,
I am using the USB-6501 to generate a serial data stream on its digital output(s). I noticed that the speed of the data steam is limited to 1kHz. Based on the information given on the NI-forum, this limitation is due to USB data transfer (minimal duration of a data transfer equals 1ms). 
 
What are my options to increase this speed (may not be hardware timed) when still considering a USB device? I have some suggestions but I don't know if/how they are relevant:
1. Instead of sending the serial bits individually over the USB (resulting each in a USB data transfer of 1ms), can I send a steam of data that is captured in a buffer of the NI-USB device? Is/how is this possible with my USB-6501 or which device do I need?
2. On the NI-forum, someone suggests to use the M-series. Based on the specs, however, the digital lines of these devices are also  timed static (the lines are not hardware timed) and as far as I know identical to the USB-6501. Is this correct?
 
Other suggestion (USB!) are welcome.
Thanks     

[julien.roland]

Hi Bjorn,
 
You are right.
 
E-series devices or static Digital module (like your USB-6501) do not have the feature needed to synchronize Digital I/O with anything else.  The DIO on these devices is purely static, and it can only be controlled with software timing.  M-Series devices have a port (port0) that can be correlated to a clock, which could be generated by a counter or an external source.  Using this clock allows you to syncrhonize DI and AI for example.
 
Hope this help.
Regards,