CT2553-PCB Aeroflex Circuit Technology, CT2553-PCB Datasheet - Page 17

• Manufacturer Part Number: CT2553-PCB
• Description: Advanced Integrated Mux Aim Hybrid For Mil-std-1553 / Sae-as15531 In Pcb Style
• Manufacturer: Aeroflex Circuit Technology

RTU MESSAGE BLOCK TRANSFER
SEQUENCE
RTU message transfer operations begin automatically upon
receipt of a valid command word from the 1553 bus. A
message transfer takes the form of an RTU Start Of
Message (SOM) cycle followed by the 1553 Message
Transfer Cycle and an RTU End Of Message (EOM) cycle
(See Figure 22).
During the RTU SOM cycle, the CT2553-PCB executes the
following actions:
The MESSAGE TRANSFER CYCLE refers to the actual
transfer of the 1553 message under control of the
CT2553-PCB. The CT2553-PCB transfers data to and from
the memory on a word-by-word basis.
Upon completion of the message transfer, the CT2553-PCB
executes an RTU End Of Message (EOM) cycle during
which the CT2553-PCB:
CURRENT AREA B/A
T/R (from command word)
SUB-ADDRESS (command word)
SCDCT2553PCB Rev A Preliminary 7/13/06
FIGURE 20 – RTU LOOK-UP ADDRESS
1. Loads the 1553 command word.
2. Reads the current area Stack Pointer to get the
3. Stores an SOM flag into the Block Status Word
4. Writes the Time Tag value into the the
5. Stores the Command Word received.
6. Reads the associated Data Block Address from
1. Generates an EOM or Error interrupt (if
2. Updates the Block Status Word: clears SOM, sets
3. Writes the Time Tag value into the Descriptor
4. Increments the Stack Pointer by 4.
address of the current Descriptor Stack Entry
(DSE).
to indicate a transfer in progress.
Descriptor Stack.
the (current area) Look-Up Table.
enabled).
EOM, and any appropriate error bits.
Stack.
15
0 0 0 0 0 0 0 1
7 6 5 4 3 2 1 0
1
17
T/R SUBADD
FIGURE 22 – RTU MESSAGE TRANSFER
FIGURE 21 – LOOK-UP TABLE EXAMPLE
0
0
0
1
1
RECEIVED COMMAND WORDS
00000
00001
00010
11110
11111
64 LOCATIONS
GENERATE EOM INTERRUPT AND
UPDATE BLOCK STATUS WORD
READ LOOK-UP TABLE USING
ERROR INTERRUPT IF ERROR
UPDATE DESCRIPTOR STACK
INCREMENT STACK POINTER
BLOCK STATUS WORD, TIME
T/R SUBADDRESS CURRENT
TRANSFER DATA TO/FROM
TAG AND COMMAND WORD
1553 INTERFACE DEVICE
1553 COMMAND WORD
READ STACK POINTER
MESSAGE COMPLETE
CONDITION DETECTED
COUNT
XXXXX
XXXXX
XXXXX
XXXXX
XXXXX
WORD
OPERATION
WAIT FOR NEXT
1553 COMMAND
AND TIME TAG
AREA BIT B/A
RECEIVED
BY FOUR
?
TABLE (A)
ADDRESS
LOOK-UP
YES
0140
0141
0142
017E
017F
*
*
*
USER DEFINED
USER DEFINED
USER DEFINED
USER DEFINED
USER DEFINED
DATA BLOCK
DATA BLOCK
Aeroflex Plainview
NO