wireless compactDAQ bitbang UART

[gharris]

Hi all,

Has anyone tried making a wireless bidirectional UART port out of a CompactDAQ device?  It looks like the 9401 module is fast enough for my baud rate (115k) but from what I've read about UART, there is an oversampling and synchronization protocol that needs to be run regularly to keep both ends of the connection in sync.  I don't yet have the device, so before I buy one any feedback would be much appreciated.

thanks,

George

[Chris-NI]

Hi gharris,

The CompactDAQ platform is not designed to operate as an embedded system with hardware-timed control, such as is required by UART.  Essentially in a WiFi CompactDAQ system, your raw digital data would be acquired by the 9401, streamed over WiFi, and received by your PC where you would then process the bits in software and create a response that would be sent back to the CompactDAQ system.  This control loop would not meet timing requirements.

There are two options you may want to consider that will allow wireless control of serial:

• Embedded device, such as CompactRIO, which has an onboard FPGA that can control a serial interface, such as the 9870 for RS232 and the 9871 for RS485.  These can be added to a wireless router to give programmatic access to the embedded serial interface.  If you want more information on this, I would recommend posting in our Real-Time Measurement and Control forums as there is more expertise there on this topic.
• Use an ethernet to serial adapter, such as the ENET-232/4 and ENET-485/4 on a WiFi-enabled router.

These are the best approaches for what it sounds like you want to do.

Regards,