9XTend
‐
PKG
‐
E™
Ethernet
RF
Modem
–
Product
Manual
v2.x4x
[2007.01.04]
©
2007
MaxStream,
Inc.,
Confidential
&
Proprietary
‐
All
Rights
Reserved
19
Bin a r y Com m a n d M ode
Sending and receiving param et er values using binary com m ands is t he fast est way t o change
operat ing param et ers of t he m odem . Binary com m ands are used m ost oft en t o sam ple signal
st rengt h [ refer t o DB ( Received Signal St rengt h) param et er] and/ or error count s; or t o change
m odem addresses and channels for polling syst em s w hen a quick r esponse is necessar y. Since t he
sending and receiving of param et er values t akes place t hrough t he sam e serial dat a pat h as 'live'
dat a ( received RF payload) , int erference bet ween t he t w o t ypes of dat a can be a concern.
Com m on quest ions about using binary com m ands:
• What are t he im plicat ions of assert ing CMD w hile live dat a is being sent or received?
• Aft er sending serial dat a, is t here a m inim um t im e delay before CMD can be assert ed?
• I s a t im e delay required aft er CMD is de- assert ed before payload dat a can be sent ?
• How does one discern bet w een live dat a and dat a received in response t o a com m and?
The CMD pin ( GPI 1) m ust be assert ed in order t o send binary com m ands t o t he m odem . The CMD
pin can be assert ed t o recognize binary com m ands anyt im e dur ing t he t ransm ission or r ecept ion
of dat a. The st at us of t he CMD signal is only checked at t he end of t he st op bit as t he byt e is
shift ed int o t he serial port . The applicat ion does not allow cont rol over w hen dat a is received,
except by wait ing for dead t im e bet w een burst s of com m unicat ion.
I f t he com m and is sent in t he m iddle of a st ream of payload dat a t o be t ransm it t ed, t he com m and
w ill essent ially be execut ed in t he or der it is r eceived. I f t he m odem is cont inuously r eceiving dat a,
t he radio w ill wait for a break in t he received dat a before execut ing t he com m and. The CTS signal
w ill fram e t he response com ing from t he binary com m and request [ refer t o figure below ] .
A m inim um t im e delay of 100 µs ( aft er t he st op bit of t he com m and byt e has been sent ) m ust be
observed before t he CMD pin can be de- assert ed. The com m and execut es aft er all param et ers
associat ed w it h t he com m and have been sent . I f all param et ers are not received w it hin 0.5 sec-
onds, t he m odem ret urns t o I dle Mode.
Not e: When param et er s ar e sent , t hey ar e t w o byt es long w it h t he least significant byt e sent fir st .
Binary com m ands t hat ret urn one param et er byt e m ust be writ t en wit h t w o param et er byt es.
Com m ands can be queried for t heir current value by sending t he com m and logically ORed ( bit -
wise) wit h t he value 0x80 ( hexadecim al) wit h CMD assert ed. When t he binary value is sent ( wit h
no param et ers) , t he current value of t he com m and param et er is sent back t hrough t he DO pin.
Figure
3
‐
06. Binary
Command
Write
then
Read
Signal
#4
is
CMD
Signal
#1
is
the
DI
signal
Signal
#2
is
the
DO
signal
from
the
radio
Signal
#3
is
CTS
I n t his graph, a value was w rit t en t o a reg-
ist er and t hen read out t o verify it . While
not in t he m iddle of ot her received dat a,
not e t hat t he CTS signal out lines t he dat a
response out of t he m odem .
IMPORTANT: In order for the modem to recognize a binary command, the RT (GPI1 Configuration)
parameter must be set to one. If binary programming is not enabled (RT parameter value is not equal
to ‘1’), the modem will not recognize that the CMD pin is asserted and therefore will not recognize the
data as binary commands.
Refer t o [ p21] for a binary program m ing exam ple ( DT com m and exam ple ret ur ns t w o byt es) .
