User's Manual

SYSTEM DESCRIPTION, INSTALLATION, AND MAINTENANCE MANUAL
eNfusion® HSD-440 Mark 2 Terminal
23-15-30 F-10
3 JUN 10
D. Understanding the Solo Word
If the data the HSD-440 Mark 2 Terminal is sending consists of only 1 or 2 octets, then
the data can be sent blind using the solo word instead of obtaining a CTS. Solo words
conform to the following rules:
• The solo word contains a 16 bit data field in bits 24–9
• Bits 31–29 are permanently set to 101b
• Solo words are not acknowledged at the link level
• Solo words are not interleaved with data file words during a data file transfer, however
if the HSD-440 Mark 2 Terminal receives a solo word during data transfer, the
HSD-440 Mark 2 Terminal shall process the solo word normally and resume file
transmission or reception.
The solo word also performs test and loop back functions to test the integrity of the ARINC
429 bus interconnection between the HSD-440 Mark 2 Terminal and the CMU.
The HSD-440 Mark 2 Terminal can send a 16 bit loop test pattern word (TEST) on the
ARINC 429 TX bus. The CMU then responds with the identical loop test pattern word
(LOOP) on the ARINC 429 RX bus. If the LOOP does not match the TEST, the HSD-440
Mark 2 Terminal indicates a TEST failure.
If the HSD-440 Mark 2 Terminal receives a TEST on its ARINC 429 RX bus, it responds
by transmitting an identical LOOP on the ARINC 429 TX bus.
A 4 bit identifier (bits 28–25) identifies the nature of the data being sent by the solo word.
The three types of data are shown in
Table F-10.
SYN The HSD-440 Mark 2 Terminal transmits a SYN word to inform the CMU
that the construction of the last file that was transmitted is confused. The
reception of a SYN word causes the CMU to abort any reception or
transmission in progress. In addition, if the CMU was transmitting, it
should re-initiate transmission of the file that was aborted.
Destination code RTS, CTS, and NTCS words use a destination code. The destination
code field (when used, bits 24–17) indicates the final destination of the
LDU. If the LDU will be used in the HSD-440 Mark 2 Terminal, the
destination code can be set to 00h. If the LDU is intended to be passed
on to another onboard system, the destination code indicates that
system.
Word count RTS and CTS words use a word count. The word count field (bits 16–9)
reflects the number of ARINC 429 words that will be transmitted in a
subsequent LDU. The maximum word count value is 255 ARINC 429
words.
Table F-9 Protocol Words and Uses (Continued)
Protocol word Uses
Table F-10 Data Types
Purpose Bits 28-25b Description
Test 0000b 16 Bit Test Pattern