XBEE PRO S1 pair has difficulty with multiple small packets

Our application has an XBEE PRO S1 (in API mode) paired with one or two others. Our communication protocol recently expanded so that we send three 6-byte messages from the XBEE in API mode to one of the other XBEEs. Often, the first two messages are received but the third does not get through. Is there any history on this? Are there any conditions or configuration issues that can cause this? And, if so, are there work-arounds or fixes?

No there is no history on this. Could it be that you are not using hardware flow control? Or could it be that you are sending a faulty API frame?

Thank you for your quick answer! Is it possible, in this thread, to ask more questions? If not, let me know and I will post again. Here are my follow-up questions: 1. Since we are not using hardware flow control, is there a way we can control the timing of our communications to avoid the loss of the third 6-byte message? And, 2. If we lost the third message because of the lack of hardware flow control, will there any other failure indication besides failure to receive it? 3. If we send a faulty API frame, does this always result in the XBEE stopping, or are their certain failures that we can look for?

If you are framing your API frames correct, you should be getting a status frame. That status frame tells you what occurred and if that packet was received.