XBee‐PRO®900HP/XBee‐PRO®XSCRFModules
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the maximum number of bytes that the transmitting module will send in one transmission event,
which may consist of many packets and retries. If the TT parameter is reached, the transmitting
module will force a random delay of 1 to RN delay slots (exactly 1 delay slot if RN is zero). Each
packet is counted only once toward TT, no matter how many times the packet is retransmitted.
Subsequent packets in acknowledged mode are similar to those in streaming mode, with the
addition of an acknowledgement between each packet, and the possibility of retransmissions.
Subsequent packets are sent without an RF initializer, as the receiving modules are already
synchronized to the transmitting module from the preceding packet(s) and they remain
synchronized for the duration of the transmission event. Each retransmission of a packet includes
an RF initializer. Once the transmitting module has sent all pending data or has reached the TT
limit, the acknowledged transmission event is completed. The transmitting module will not
transmit again for exactly RN delay slots, if the local RN parameter is set to a nonzero value. The
receiving module will not transmit for a random number of delay slots between 0 and (RN-1), if
the local RN parameter is set to a nonzero value. These delays are intended to lessen congestion
following long bursts of packets from a single transmitting module, during which several receiving
modules may have themselves become ready to transmit.
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