Reference Manual AFDX / ARINC 664 Application Interface Library
177
Section 4 – Function Reference: Receiver Functions
Figure 4.4.2.8-1: RX UDP Message Buffer Layout
UDP Message Buffer Layout
31
24
23
16
15
8
7
0
Time Tag High
Time Tag Low
Message Size
UDP Heade
r
Error Information
UDP Fr
ame
Received UDP- FRAME
(sampling message: up to UDP payload (1 – 1471 bytes
queuing message: up to 8Kbytes)
T
T
Y
Y
_
_
F
F
D
D
X
X
_
_
U
U
D
D
P
P
_
_
H
H
E
E
A
A
D
D
E
E
R
R
This is a structural description of the UDP header
typedef struct _fdx_udp_header {
TY_FDX_FW_IRIG_TIME
x_FwIrigTime;
AiUInt32
ul_MsgSize;
AiUInt32
ul_ErrorInfo;
}
TY_FDX_UDP_HEADER;
T
T
Y
Y
_
_
F
F
D
D
X
X
_
_
F
F
W
W
_
_
I
I
R
R
I
I
G
G
_
_
T
T
I
I
M
M
E
E
x
x
_
_
F
F
w
w
I
I
r
r
i
i
g
g
T
T
i
i
m
m
e
e
The Firmware IRIG Time Tag information is from the last received message. For a queuing
port where the messages can be fragmented, it is the Time Tag of the last received fragment.
typedef struct {
AiUInt32
ul_TtHigh;
AiUInt32
ul_TtLow;
} TY_FDX_FW_IRIG_TIME;
A
A
i
i
U
U
I
I
n
n
t
t
3
3
2
2
u
u
l
l
_
_
T
T
t
t
H
H
i
i
g
g
h
h
;
;
Timetag word in firmware format. The higher part of the time tag, contains the minutes of
hour, hours of day and day of year.
For further description see Firmware specification.
A
A
i
i
U
U
I
I
n
n
t
t
3
3
2
2
u
u
l
l
_
_
T
T
t
t
L
L
o
o
w
w
;
;
Timetag word in firmware format. The lower part of the time tag, contains the
Microseconds of second, seconds of minutes and minutes of hour.
To get a ‘C’ structured information of the Time Tag you can use the functions
FdxFwIrig2StructIrig ().
A
A
i
i
U
U
I
I
n
n
t
t
3
3
2
2
u
u
l
l
_
_
M
M
s
s
g
g
S
S
i
i
z
z
e
e
;
;
UDP payload size in bytes of received Frame.
