Communicating with a large number of remote units

XBee & XBee Gateway XBee - 802.15.4
1

Hi everybody,

I am trying to build a system based on the Xbee Pro OEM platform. Current setup is one coordinator and several remote units. If all goes well the number of remote units may grow (> 100). I need to collect the largest possible number of samples per second from one remote unit at a time.

I have tried using the ATIR command to decrease the interval between samples in one remote unit (to 0x01), and increase it in all other units (to 0xFFFF), with limited success. Remote AT commands are mostly unacknowledged, unless baud rate is limited to 38400 (I think this has to do with full duplex simulation).

I have increased the number of samples per message to the maximum (7 samples per message when using 5 ADCs), is there anything I can do to improve performance? Otherwise - is there a Digi product more suited for my needs?

Another very important question has to do with sample timing: when using multiple ADCs and multiple samples per message - would you know if the first sample for each ADC (within a specific message) is taken exactly at the same time? Are the ADCs sampled simultaneously or one at a time?

Thanks and best regards, Jonathan.

2

You might want to check page 13 of the 10cx product manual, where it says that sampling at periods of less than 20mS is not recommended.

It sounds as though your bandwidth requirement may be a little too demanding here.

3

Thank you for your response. Would you be able to recommend an alternative platform that can can provide higher bandwidths?

What can I do to improve performance, other than keeping to a minimum of 20ms between samples?

Thanks, Jonathan.