4Links EtherSpaceLink Series, User Manual

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EtherSpaceLink-RG408
EtherSpaceLink family User Manual
Th e E t h e rS p ac eL i n k p r o t o c ol c o m po nents m a y j u st be r e po r ted u s i n g
EtherSpaceLink_read_packet_full()
w i t
h
t
h
e
special_action
p
a
r
a
mete r set t o
EtherSpaceLink_REPORT_SPECIAL_DATA
.
In t h i s ca se , t h e l en g t h o f t h e p ac k et r et u r ned m a y be ne g a t iv e , i nd i ca t i n g t ha t a s p e c i a l p ac k et ha s
been r e
c
e iv ed.
EtherSpaceLink_read_packet_full()
m
u
st t
h
en be
ca ll
ed
w
i t
h
t
h
e
special_action
p a r a mete r set t o
EtherSpaceLink_RETURN_SPECIAL_DATA
v a lu e.
Po
s i t iv e
- l
en g t
h p ac k
ets
c o
nt
a
i n S
p ac
e
W
ir e d
a
t
a
.
Th e E t h e rS p ac eL i n k p r o t o c ol c o m po nents m a y t rigg e r a ca ll b ac k ac t i o n u s i n g
EtherSpaceLink_read_packet_full()
w
i t
h
t
h
e
special_action
p a
r
a
mete r set t
o
EtherSpaceLink_CALLBACK_SPECIAL_DATA
.
Th
e
ca ll
b
ac k f u
n
c
t i
o
n m
u
st be
p
r e vi
ou
s
ly
r e gi ste r ed
w
i t
h
EtherSpaceLink_read_packet_special_callback()
. Wh en a s p e c i a l p ac k et ha s
been r e
c
e iv ed , t
h
e
c o
rr es
po
nd i n g
f u
n
c
t i
o
n i s
ca ll
ed t
o
de
l
iv e r i t.
P r o gr a mm i n g t h e r e c e p t i o n o f s p e c i a l d a t a u s i n g ca ll b ac k s h e lp s t o i s ol a te t h e ha nd l i n g o f t h i s
i n
f o
r m
a
t i
o
n
f
r
o
m t
h
e S
p ac
e
W
ir e d
a
t
a
.
Th ese te ch n i q u es m a y be u sed w i t h m a n y c o mb i n a t i o ns o f ca ll b ac k s , r e po r ts a nd i mmed i a te p ac k et
de l iv e r y . P e r
ha
p s t
h
e
EtherSpaceLink_RETURN_xx_DATA
me
cha
n i sm i s t
h
e e
a
s i est t o u se; t
h
e
p ac k ets a r e de l iv e r ed w i t h l e a st i nte r f e r en c e.
14.5. 3 . A synch r onous I ssues d u ri n g S t a tus Poll i n g
Th
e
C A P
I
c o
nt
a
i ns
a
n
u
mbe r
o f f u
n
c
t i
o
ns t
ha
t r e
q u
est i n
f o
r m
a
t i
o
n
f
r
o
m
a
n
E
t
h
e rS
p ac
eL i n
k u
n i t
a
nd
t h en w a i t u nt i l t h e y r e c e iv e a r es po nse , po tent i a lly t h r ow i n g a w a y S p ac e W ir e d a t a t ha t i s r e c e iv ed i n
t
h
e me
a
nt i me.
Th
i s i s
a
ne
c
ess
a
r
y
be
ha
vi
ou
r be
ca u
se i t i s i m
po
ss i b
l
e t
o p
r ed i
c
t
h ow
m
u ch
S
p ac
e
W
ir e
d a t a m ig h t be i nte r l e a v ed w i t h t h e r es po nse , a nd t h u s h ow m u ch b u ff e r s p ac e t o a llo ca te. Th ese
r
ou
t i nes s
h oul
d t
h
e r e
f o
r e n
o
t be
ca ll
ed i
f
t
h
e r e i s
a
n
y
ri s
k
t
ha
t S
p ac
e
W
ir e d
a
t
a w
i
ll
be de
l
iv e r ed
a s y n ch r o n ou s ly b y t h e E t h e rS p ac eL i n k u n i t. A ppl i ca t i o ns t ha t poll a S p ac e W ir e -c o nne c ted i nst r u ment
(m
a y
be
u
s i n g t
h
e S
p ac
e
W
ir e R em
o
te
M
em
o
r
y Acc
ess
P
r
o
t
o c ol
( R
MA P
))
w
i
ll
n
o
t r e
c
e iv e s
u ch
t r
aff
i
c
a nd ca n u se a n y o f t h ese r ou t i nes a t a n y t i me.
Th
e
f u
n
c
t i
o
ns
w h
i
ch
e x
h
i b i t t
h
i s be
ha
vi
ou
r
fa ll
i nt
o
t
wo ca
te g
o
ri es:
EtherSpaceLink_get_manufacturer_string()
,
EtherSpaceLink_get_HWA()
,
EtherSpaceLink_get_product_string()
a
nd
EtherSpaceLink_get_number_of_links()
s
h oul
d be
ca ll
ed
a
t t
h
e st
a
r t
o f a
n
A P
I
p r o gr
a
m , be
f
o r e t
h
e S p
ac
e
W
ir e l i n k s
a
r e en
a
b l ed u s i n g
EtherSpaceLink_set_mode()
.
Th
i s
w
i
ll
be r e
l
i
a
b
l
e.
I f
EtherSpaceLink_write_buffer_empty()
,
EtherSpaceLink_link_connected()
o
r
EtherSpaceLink_get_control_packet()
a r e ca ll ed t o dete r m i ne t h e st a t u s o f a
S
p ac
e
W
ir e
l
i n
k a
t t
h
e s
a
me t i me
a
s
a
n
y o f
t
h
e
l
i n
k
s
a
tt
ach
ed t
o
t
h
e
E
t
h
e rS
p ac
eL i n
k u
n i t i s
r et u r n i n g S p ac e W ir e t r aff i c , s o me o f t ha t S p ac e W ir e d a t a m ig h t be lo st. S u ch d a t a lo ss i s i nd i ca ted
b
y
t
h
e
fa
i
l
i n g r es
ul
t
c o
de t
ha
t i s r et
u
r ned.
4Links Limited
www.4Links.co.uk
support@4Links.co.uk
page 44 of 110
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