XStream‐PKG‐E™ Ethernet RF Modem – Product Manual v4.2B5
Cy clic Slee p ( SM = 3 - 8 )
Cyclic Sleep is t he Sleep Mode in w hich t he XStream Modem ent er s into a low - power st ate and
awakens per iodically to determ ine if any tr ansm issions ar e being sent .
When Cyclic Sleep set t ings ar e enabled, t he XStream Modem goes int o Sleep Mode after a user -
defined period of inact iv it y ( no t ransm ission or recept ion on the RF channel) . The user - defined
per iod is det er m ined by ST ( Tim e befor e Sleep) Com m and.
While t he m odem is in Cy clic Sleep Mode, DO2 (
) is de- asser t ed ( high) to indicat e t hat
dat a should not be sent to t he m odem dur ing t his t im e. When t he m odem aw akens to listen for
data, DO2 is asser t ed and any dat a receiv ed on t he DI Pin is tr ansm it ted. The PWR pin is also
de- asser t ed ( low ) w hen t he m odem is in Cy clic Sleep Mode.
The m odem r em ains in Sleep Mode for a user - defined per iod of t im e r anging fr om 0.5 seconds to
16 seconds ( SM Par am et er s 3 t hr ough 8) . Aft er t his int er v al of t im e, t he m odem r et urns to I dle
Mode and list ens for a v alid dat a pack et for 100 m s. I f t he m odem does not detect v alid dat a ( on
any fr equency ) , t he m odem ret ur ns to Sleep Mode. I f v alid dat a is detected, t he m odem
t r ansit ions into Receiv e Mode and receiv es incom ing RF pack et s. The m odem t hen r et ur ns t o
Sleep Mode aft er a Per iod of inact iv it y t hat is det er m ined by ST “ Tim e befor e Sleep” Com m and.
The m odem can also be configur ed to w ak e from cy clic sleep w hen SLEEP/ DI 3 is de- asser ted
( low ) . To configur e a m odem to oper at e in t his m anner , PW ( Pin Wak e- up) Com m and m ust be
issued. Once DI 3 is de- asser t ed, t he m odem is for ced int o I dle Mode and can begin tr ansm it t ing
or r eceiv ing dat a. I t r em ains act iv e unt il no dat a is det ect ed for t he per iod of t im e specified by
t he ST Com m and, at w hich point it r esum es it s low - power cyclic st at e.
Note: The cyclic interval time defined by SM (Sleep Mode) Command must be shorter than the interval
time defined by LH (Wake-up Initializer Timer). (Refer to figures below.)
Cy clic Sca n n ing.
Each RF t r ansm ission consist s of an RF I nit ializer and pay load. The w ake- up
init ializer cont ains init ializat ion inform at ion and all receiv ing m odem s m ust w ak e dur ing t he
w ak e- up init ializer por t ion of dat a tr ansm ission in order t o be sy nchronized w it h t he t r ansm it t ing
m odem and r eceiv e t he dat a.
Figure 3‐06. Correct Configuration (LH > SM)
Length of the wake‐up initializer exceeds the time interval of Cyclic Sleep. The receiver is guaranteed to detect
the wake‐up initializer and receive the accompanying payload data.
Figure 3‐07. Incorrect Configuration (LH < SM)
Length of wake‐up initializer is shorter than the time interval of Cyclic Sleep. This configuration is vulnerable
to the receiver waking and missing the wake‐up initializer (and therefore also the accompanying payload data).
© 2014 Digi International Inc.
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