Network configurations Basic communications
XBee®-PRO 900HP/XSC RF Modules
233
Streaming Mode data flow
n Streaming Mode state diagram (TX Module)
n Events and processes in this mode are common to all of the other RF Modes.
Note When the device is streaming data, RB and RO parameters are only observed on the first packet.
After transmission begins, the TX event continues uninterrupted until the DI buffer is empty or it
reaches the streaming limit (TT Command). As with the first packet, the payload of each subsequent
packet includes up to the maximum packet size (PK Command).
The transmitting device specifies the streaming limit (TT Command) as the maximum number of bytes
the transmitting device can send in one transmission event. After it reaches the TT parameter
threshold, the transmitting module forces a random delay of 1 to RN delay slots (exactly 1 delay slot if
RN = 0).
The device sends subsequent packets without an RF initializer since receiving devices stay
synchronized with the transmitting device for the duration of the transmission event (from preceding
packet information). However, due to interference, some receiving devices may lose data (and
synchronization to the transmitting device), particularly during long transmission events.
Once the transmitting device sends all pending data or has reaches the TT limit, the transmission
event ends.
The transmitting device will not transmit again for exactly RN delay slots if the local (that is, the
transmitting device’s) RN parameter is set to a non-zero value.
The receiving devices will not transmit for a random number of delays between 0 and (RN-1) if the
local (that is, the receiving module’s) RN parameter is set to a non-zero value.
These delays are intended to lessen congestion following long bursts of packets from a single
transmitting device, during which several receiving devices may have become ready to transmit.
Repeater mode
Characteristics
n Self-organizing - No route configuration is necessary.
n Self-healing / Fault-tolerant.
n Low power consumption and Minimized interference.
n Network throughput is determined by number of hops, not by number of repeaters. Multiple
repeaters within range of source node count as one hop.
n Supports “transparent” multi-drop mode or addressed data filtering mode.
n Duplicate RF packets are automatically filtered out.
n All packets propagate to every node in the network (filtering rules apply).
n Broadcast communications - each packet comes out every node exactly once.
n Addressed communications - all devices see every packet. Only the device with a matching
address forwards it to the DO buffer (UART IN).
n Devices transmit and forward data entering the network on any device through every repeater
device until it reaches the ends of the network.
n Each repeater repeats a packet only once.
To Next Page
Loading...
Need help?
General
