HI-6121PQMF HOLTIC [Holt Integrated Circuits], HI-6121PQMF Datasheet - Page 30

• Manufacturer Part Number: HI-6121PQMF
• Description: MIL-STD-1553 Remote Terminal ICs
• Manufacturer: HOLTIC [Holt Integrated Circuits]

COMMAND ILLEGALIZATION TABLE, Cont.
SA31 mode commands. Since either subaddress
indicates a mode command, the subaddress 0 table words
should match the subaddress 31 table words in each
quadrant.
Table entries from 0x0142 to 0x017D do not have to be
programmed. These correspond to broadcast transmit
subaddress commands (undefined by MIL-STD-1553B)
and are always invalid. There is no terminal response.
Addressing for the Illegalization Table is derived from the
command word
Count (Mode Code) field and the command’s broadcast
vs. non-broadcast status as shown below in Figure 3:
Bit Fields Comprise Each Received Command Word
Figure 5 shows individual bit locations in the Illegalization
Table for broadcast and non-broadcast variants of all mode
commands defined by MIL-STD-1553B. Locations are
also identifed for reserved mode codes and undefined
mode code commands.
The following examples illustrate how the Illegalization
Table is initialized to distinguish between legal and illegal
commands when “illegal command detection” is being
used. Remember: If the terminal does not use illegal
command detection, the table is left in its post-
state, with all table locations reset to 0x0000. In this case,
all command responses are “in form”.
For “subaddress commands”
commands or transmit commands) individual table bits
correspond to word counts specified in the received
command word. If a bit is 0, the corresponding word count
is legal. If a bit is 1, the corresponding word count is illegal.
For example, transmit commands to subaddress 1 are
controlled by the words at 0x01C2 and 0x01C3. In Figure
4, these words are located in the “RT Address Transmit”
FIGURE 3. Deriving the Illegalization Table Address
0 0 0 0 0 0 0 1
Command
Sync
TA4:0 = 11111
From the Received Command Word
Terminal
Address
else “1”
TA4:0
T/
“0” if
R
bit, subaddress field, MSB of the Word
T/
Bit
R
Subaddress
SA4:0
(ordinary receive
(Mode Code)
Word Count
HOLT INTEGRATED CIRCUITS
WC4:0
Table
Address
MR
HI-6120, HI-6121
reset
P
30
block. The word stored at 0x01C3 controls subaddress 1
transmit commands having word counts 16 to 31. The
word stored at 0x01C2 controls subaddress 1 transmit
commands having word counts 1 to 15 or 32. (Reminder:
In MIL-STD-1553B, zero corresponds to 32 words.)
Word at 0x01C3 (subaddress 1: 31 to 16 words)
Bit
Words 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
Word at 0x01C2 (subaddress 1: 15 to 1 & 32 words)
Bit
Words 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 32
If the word stored at 0x01C3 = 0xFFFF and the word stored
at 0x01C2 = FF0F, then commands with 4, 5, 6, or 7 data
words are the only legal transmit commands for
subaddress 1 and all other word counts are illegal. Receive
commands and broadcast receive commands for
Subaddresses1 through 30 are encoded similarly.
For “mode code commands”
command word subaddress field equal to 00000 or 11111
binary) individual table bits correspond to individual mode
code values. Here “transmit” and “receive” simply indicate
the state of the command word
0-15, the
data is not transacted when fulfilling these commands.)
Figure 5 summarizes the 16 Illegalization Table locations
for mode commands. These locations are scattered
throughout the overall Illegalization Table shown in Figure
4. Remember: the host must initialize all table locations
corresponding to both subaddress 0 and subaddress 31
(11111 binary).
Consider an example in which all reserved and all
undefined mode commands are illegal. If all defined
transmit mode commands are legal except MC0 (”dynamic
bus control”) the eight table entries for transmit mode
commands would be:
0x01FF and 0x01C1 = 1111 1111 1111 0010 = 0xFFF2
0x01FE and 0x01C0 = 1111 1110 0000 0001 = 0xFE01
0x017F and 0x0141 = 1111 1111 1111 1111 = 0xFFFF
0x017E and 0x0140 = 1111 1110 0000 0101 = 0xFE05
The receive mode command words are encoded similarly.
Continuing the same example where all reserved and all
undefined mode commands are illegal: If all defined
receive mode commands are legal, the eight table entries
for receive mode commands would be:
0x01BF and 0x0181 = 1111 1111 1100 1101 = 0xFFCD
0x01BE and 0x0180 = 1111 1111 1111 1111 = 0xFFFF
0x013F and 0x0101 = 1111 1111 1100 1101 = 0xFFCD
0x013E and 0x0100 = 1111 1111 1111 1111 = 0xFFFF
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
T/
R
bit does not indicate data direction since
T/
R
bit. (For mode codes
(characterized by