Not receiving enough frames after I use XCTU to set IR on Pro s2b endpoint.

Question

Hi all,

I am trying to transmit 3 channels of analog accelerometer data at 30 SPS and 57600 Baud. I have pin hibernate on the endpoint with the sleep pin tied low.

But

- first of all, the behaviour of the IR parameter doesn't match the label description on XCTU, which seems to suggest that the value of his parameter represents the number of ms between samples.

- when I set the value of IR, it doesn't seem to impact in a predictable way on the number of "sample frames" that are transmitted by the endpoint. At the moment I have IR set to 32, which you would think would result in just over 30 frames/sec. but the max that i have been able to get is 12 frames/sec.

- I have the baud rate at a relatively high value of 57600 I would have thought that this was high enough with lots to spare to manage 30 frames / second. At 26 bytes per frame, it should only need 9600 baud.(?)

Any suggestions gratefully accepted
Thanks
nomad_bee

Answer 1

You are not taking into account the latency and throughput differences on a mesh based product vs a Point to point product. A mesh based product can't sample and transmit its data at 30 times per second. If you are lucky it would be closer to 10 times per second.

Comments

Hi mvut - thanks for your reply. The pair of S2Bs was what was available to me, so I tried them out. I had gathered from other posts that pairing off the SH SL and DH / DL of endpoint and controller would make the S2Bs behave as point to point devices. I would also like to retain the relatively long range of the S2Bs. You are saying that I need to pick another XBee device then?

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While you can configure the radios for a point to point connection, it will still do it in a mesh fashion regardless (total overall through put of 30kbps at best).  In reality, it would be better for you to use one of the Point to point products such as the 802.15.4 modules that can handle the lower latencies and high bandwidths (80kbps bandwidth).