4Links EtherSpaceLink Series, User Manual

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EtherSpaceLink-RG408
EtherSpaceLink family User Manual
I f o ne o f t h ese ac t i o ns i s n o t s p e c i f i ed , t h o se p ac k ets w i ll be d i s ca r ded.
EtherSpaceLink_
DISCARD_SPECIAL_DATA
I g n o r e a n y s p e c i a l d a t a p ac k ets [ de fa ul t ] .
EtherSpaceLink_
REPORT_SPECIAL_DATA
R et a i n t h e s p e c i a l d a t a p ac k et i n a b u ff e r a nd r e po r t
i ts l en g t h .
EtherSpaceLink_
RETURN_SPECIAL_DATA
D e l iv e r t h e s p e c i a l d a t a i n t h e giv en b u ff e r .
EtherSpaceLink_
CALLBACK_SPECIAL_DATA
Ca
ll t
h
e r e gi ste r ed
ca
ll b
ac
k p r o
c
ed u r e t o
ha
nd l e t
h
e
s p e
c
i
a
l d
a
t
a
b u
ff
e r . I
f
n o s u
ch ca
ll b
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c
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h
en d i s
ca
r d t
h
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c
i
a
l d
a
t
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p
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S ee
EtherSpaceLink_read_packet_special_
callback()
.
Output p ara mete r s
terminator
i nd i
ca
tes
w ha
t te r m i n
a
t
o
r, i
f a
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,
w a
s r e
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Retu r ns
≥ 0 Th e n u mbe r o f d a t a b y tes ac t u a lly i n t h e r e c e iv e b u ff e r .
-
1
A
n e rr
o
r
o cc u
rr ed.
-N- 2 I f t h e r e c e iv ed d a t a w a s “s p e c i a l” d a t a a nd t h e ac t i o n r e q u ested w a s t o r e po r t s u ch
d
a
t
a
t
h
en t
h
e r et
u
r ned v
a lu
e i s ne g
a
t iv e: t
h
e
a
bs
olu
te v
a lu
e m i n
u
s 2 be i n g t
h
e n
u
mbe r
o f s p e c i a l d a t a b y tes a v a i l a b l e. (e. g . a r et u r n v a lu e o f - 3 i nd i ca tes a s p e c i a l p ac k et
c o
nt
a
i n i n g 1 b
y
te i s
a
v
a
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E xa mple
U s i n g t
h
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a
me b
u ff
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a
EtherSpaceLink ESL_unit;
char buffer[1024];
int n;
int EOP;
ESL_unit = EtherSpaceLink_open ( "192.168.3.40" );
EtherSpaceLink_set_mode ( ESL_unit, EtherSpaceLink_LINK_mode_normal );
n = EtherSpaceLink_read_packet_full ( ESL_unit, buffer, sizeof(buffer), &EOP,
EtherSpaceLink_RETURN_SPECIAL_DATA
);
// the terminator value in ‘EOP’ tells us what sort of data we have
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