XBee‐PRO®900HP/XBee‐PRO®XSCRFModules
©2014DigiInternationalInc. 126
SY (Time before Initialization) Command
TR (Transmit Error Count) Command
Command Summary
Description
AT Command: ATSY
<Networking> SY Command keeps a communication channel
open as long as module transmits or receives before the active
connection expires. It can be used to reduce latency in a query/
response sequence and should be set 100 ms longer than the
delay between transmissions. This command allows multiple
Modules to share a hopping channel
for a given amount of time after receiving data. By default, all
packets include an RF initializer that contains channel
information used to synchronize any listening receivers to the
transmitter’s hopping pattern. Once a new module comes
within range, it is able to instantly synchronize to the
transmitter and start receiving data. If no new modules are
introduced into the system, the synchronization information
becomes redundant once modules
have become synchronized.
SY Command allows the modules to remove this information
from the RF Initializer after the initial synchronization. For
example, changing the SY Parameter to 0x14 (20 decimal)
allows all modules to remain in sync for 2
seconds after the last data packet was received.
Synchronization information is not re-sent unless transmission
stops for more than 2 seconds. This command allows
significant savings in packet transmission time.
Warning: Not recommended for use in an interference-prone
environment. Interference can break up the session and the
communications channel will not be available again until SY
time expires. With SY set to zero, the channel session is opened
and closed with each transmission - resulting in a more robust
link with more latency.
Binary Command: 0x17 (23 decimal)
Parameter Range:0 – 0xFF
[x 100 milliseconds]
Default Parameter Value: 0 (Disabled -
channel initialization information is sent
with each RF packet.)
Number of bytes returned: 1
Command Summary
Description
AT Command: ATTR <Diagnostics> TR Command records the
number of retransmit failures.
This number is incremented each time a
packet is not acknowledged within
the number of retransmits specified by
the RR (Retries) Command. It
therefore counts the number of packets
that were not successfully received
and have been dropped.
The TR Parameter is not non-volatile and
will therefore be reset to zero
each time the module is reset.
Binary Command: 0x1B (27 decimal)
Parameter Range:0 – 0xFFFF
Default Parameter Value: 0
Number of bytes returned: 2
Related Commands: RR (Retries)
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