Xbee Analog Adapter A/D sample rate limitation?

I’ve put together an application using two 802.15.4 Analog I/O Adapters. I’ve set the sampling to 16msecs per sample (IR=10, IT=20). I receive the correct amount of data per second back from the module and at first glance everything’s working correctly.

However, there seems to be a problem with the data. If I apply a triangle wave to the input, what I see in the data is a series (6-10) of identical readings then 4-10 different readings. The data values go up and down as they should but they do not change on each sample. It appears that one reading from the A/D is sent back n times. I get this behavior from both modules.

Sample data: A,A,A,A,A,A,45,45,45,45,45,45,45, 61,61,61,61,61,61,61

I spoke to someone in tech support and they said to send the adapters back for repair. I’m very doubtful that the problem is with these specific modules - though I suppose it is remotely possible if extremely unlikely. I’m wary of losing another few weeks with sending these modules back and forth if there is a design issue.

So my questions are:

  1. Has anyone else ever seen this behavior with these modules?

  2. Has anyone else set the sample rate to <= 16 msecs, looked at the data and confirmed that they are getting real data at the requested rate?

Thanks for your help