
RTS-8
1.4 Mode Code and Subaddress
The UT1760A RTS provides two modes of illegal
subaddress decoding, one meeting MIL-STD-1760A
Notices I and II, and the other meeting MIL-STD-1760A
Notice III. In addition, the device has automatic internal
illegal command decoding for reserved MIL-STD-1553B
mode codes. These definitions are extracted from MIL-
STD-1760A and reviewed in section 1.5 of this document.
Upon command word validation and decode, status pins
MCSA(4:0) and MC/SA become valid. Status pin MC/SA
will indicate whether the data on pins MCSA(4:0) is mode
code or subaddress information. Status Register bits 0
through 5 contain the same information as pins MCSA(4:0)
and MC/SA. The system designer can use signals
MCSA(4:0), MC/SA, BRDCST, RTRT, etc. to illegalize
mode codes, subaddresses, and other message formats
(broadcast and RT-to-RT) via the Illegal Command
(ILLCOM) input to the part.
RTS MODE CODE HANDLING PROCEDURE
T/R
Mode Code
0
10100
Function
Operation
Selected Transmitter Shutdown
2
1. Command word stored
2. MERR pin asserted
3. MERR bit set in Status Register
4. Status word transmitted
1. Command word stored
2. MERR pin asserted
3. MERR bit set in Status Register
4. Status word transmitted
1. Command word stored
2. Data word stored
3. Status word transmitted
1. Command word stored
2. MERR pin asserted
3. MERR bit set in Status Register
4. Status word transmitted
1. Command word stored
2. Status word transmitted
1. Command word stored
2. Status word transmitted
1. Command word stored
2. Status word transmitted
1. Command word stored
2. Alternate bus shutdown
3. Status word transmitted
1. Command word stored
2. Alternate bus enabled
3. Status word transmitted
1. Command word stored
2. Terminal Flag bit set to zero and disabled
3. Status word transmitted
1. Command word stored
2. Terminal Flag bit enabled, but not set to logic one
3. Status word transmitted
1. Command word stored
2. Status word transmitted
1. Status word transmitted
2. Last command word transmitted
1. Command word stored
2. Status word transmitted
3. Data word transmitted
1. Command word stored
2. Status word transmitted
3. Data word transmitted
0
10101
Override Selected Transmitter
Shutdown
0
10001
Synchronize (w/Data)
1
00000
Dynamic Bus Control
2
1
00001
Synchronize
1
1
00010
Transmit Status Word
3
1
00011
Initiate Self-Test
1
1
00100
Transmitter Shutdown
1
00101
Override Transmitter Shutdown
1
00110
Inhibit Terminal Flag Bit
1
00111
Override Inhibit Terminal Flag
1
01000
Reset Remote Terminal
1
1
10010
Transmit Last Command
Word
Transmit Vector Word
1
10000
1
10011
Transmit BIT Word
Notes:
1. Further host interaction required for mode code operation.
2. Reserved mode code; A) MERR pin asserted, B) MESS ERR bit set, C) status word transmitted (ME bit set to logic one).
3. Status word not affected.
4. Undefined mode codes are treated as reserved mode codes.