User's Manual

SYSTEM DESCRIPTION, INSTALLATION, AND MAINTENANCE MANUAL
eNfusion® HSD-440 Mark 2 Terminal
23-15-30 F-9
3 JUN 10
A. Understanding the Full Binary Data Word
This word shall transmit 5 nibbles of data. See ARINC 429P3 Attachment 11 for details.
B. Understanding the Partial Binary Data Word
This word shall transmit 4 or less nibbles of data. See ARINC 429P3 Attachment 11 for
details.
C. Understanding Protocol Words
The protocol words are shown in Table F-9. The protocol identifier occupies bits 28-25
of the protocol word.
Table F-9 Protocol Words and Uses
Protocol word Uses
RTS
(Request to Send)
The HSD-440 Mark 2 Terminal issues an RTS to the CMU when it is
ready to send an LDU. The RTS contains a destination code (bits 24–
17) and a word count (bits 16–9).
CTS
(Clear to Send)
When the HSD-440 Mark 2 Terminal receives an RTS, it issues a CTS
to the CMU when the CMU is ready to send an LDU. The CTS contains
the same destination code and word count as the HSD-440 Mark 2
Terminal received in the RTS.
Bit 11 of the Status Word Label 270 from the HSD-440 Mark 2 Terminal
indicates when a satellite link is available to proceed if this is a ground
destination message.
NCTS
(Not Clear to Send)
When the HSD-440 Mark 2 Terminal either receives a valid RTS and is
not ready to accept data or receives an RTS with an invalid destination
or word count, it responds with an NCTS. The NCTS contains a
destination code (bits 24–17).
NAK
(negative
acknowledgement)
If the HSD-440 Mark 2 Terminal notes a missing SOT or EOT word,
parity error, word count error, CRC error, or time out error, it will respond
with a NAK. The NAK contains the same file sequence number in bits
24–17 as the SOT word.
ACK
(acknowledgement)
If the HSD-440 Mark 2 Terminal transfers each word within the
designated time and with odd parity, correct word count, and verified
CRC. The LDU is either next, first, or a duplicate. Then the HSD-440
Mark 2 Terminal sends an ACK. The ACK word contains the file
sequence number (bits 24–17) and the LDU sequence number (bits 16–
9).
ALO
(aloha)
The HSD-440 Mark 2 Terminal can initiate BOP V1 communication by
sending an ALO word out on the bus.
The first ALO word that the HSD-440 Mark 2 Terminal transmits contains
the highest version number it supports (bits 12–9). This word determines
the correct protocol to use for the exchange. The ALO also sends its own
SAL (bits 24–17).
ALR
(aloha response)
When the HSD-440 Mark 2 Terminal receives an ALO word, it leaves its
present task and responds with an ALR word. The response contains
the protocol version level supported.