78
Reference Manual AFDX / ARINC 664 Application Interface Library
Section 4 – Function Reference: Transmitter Functions
A
A
i
i
U
U
I
I
n
n
t
t
3
3
2
2
u
u
l
l
_
_
F
F
r
r
a
a
m
m
e
e
H
H
e
e
a
a
d
d
e
e
r
r
W
W
o
o
r
r
d
d
_
_
1
1
Frame Header Word 1 contains following information
Value
Bit
Description
RSF-Port
31..29
This field contains the information about the special transmit functionality
for the current frame in
redundant operation mode. This functionality allows either to delay the
frame transmission on the
defined physical port or it allows to suppress the transmission of the
frame on the defined physical
port. This functionality is only provided in redundant operation mode.
0 0 0
0 0 1
0 1 0
1 0 1
1 1 0
default
Both packets are sent simultaneously ( without skew )
Packet on Network A is delayed by the Skew value, related to Network B
Packet on Network B is delayed by the Skew value, related to Network A
Packet on Network A is suppressed at redundant transmission
Packet on Network B is suppressed at redundant transmission
reserved
Reserved 28
reserved
IFG-CNT
Interframe gap
This 14bit value defines the minimum Interframe gap between the
preceding frame and the current frame. The Interframe gap is defined
in gap time units (GTU), which are dependent on the
transmission speed mode. A GTU is time to transmit four data
bits, which means 40ns at 100Mbit/s operation mode and 400ns at
10Mbit/s operation mode.
The range of the Interframe Gap value starts from four GTUs up to
16383 GTUs. If less than 24 GTUs are defined, the connected
Receive devices on the network may (shall) detect an 'Short
Interframe Gap' error condition. The maximum provided Interframe gap
will be up to appr. 655us 100Mbit/s operation mode or up to appr.
6,55ms 10Mbit/s operation mode.
Please Note, the Interframe gap is only applicable, if two frames
are loaded consecutive to the Transmit FIFO. In this case, the
Interframe gap applied by the Encoder device.
Reserved 13..11 reserved
Byte Count 10..0
This field contains the number of bytes, which shall be transmitted within
the AFDX- MAC- Frame,
including the CRC field. Since this value is programmable, Short
frame conditions ( below
64bytes) as well as Frame too Long conditions ( more as 1518 bytes )
can be generated. If Byte
count values less than 60 bytes are programmed, no proper frame
transmission can be
guaranteed.
Note: Byte Count values less than 40 bytes and more than 2000bytes
are not allowed and may be cause unrecoverable transmit operation
errors.
