Aeroflex Circuit Technology

21

SCDCT2553 REV B 8/6/99 Plainview NY (516) 694-6700

DYNAMIC BUS CONTROL (00000)

MESSAGE SEQUENCE = DBC * STATUS

The CT2553 responds with status. If the subsystem wants control of the bus, it must set DBACC within 2.5us after NBGRT.

ERROR CONDITIONS

1. Invalid Command. No response, command ignored.

2. Command Followed by Data Word. No status response. Bits set: message error (SW), High word Count (BIT Word).

3. T/R bit Set to Zero. No status response. Bits set: message error (SW), T/R Error (Bit Word).

4. Zero T/R bit and Broadcast Address. No status response. Bits set: message error, broadcast received (SW), Illegal Mode Code, T/R

Error (BIT Word).

5. Broadcast Address. No status response. Bits set: message error, broadcast received (SW), Illegal Mode Code (BIT Word).

SYNCHRONIZE WITHOUT DATA WORD (00001)

MESSAGE SEQUENCE = SYNC * STATUS

The CT2553 responds with status. If sent as a broadcast, the broadcast receive bit will be set and status response suppressed.

ERROR CONDITIONS

1. Invalid Command. No response, command ignored.

2. Command Followed by Data Word. No status response. Bits set: message error (SW), High Word Count (BIT Word).

3. T/R bit Set to Zero. No status response. Bits set: message error (SW), T/R Error (BIT Word).

4. Zero T/R bit and Broadcast Address. No status response. Bits set: message error, broadcast received (SW), Illegal Mode Code, T/R

Error (BIT Word).

TRANSMIT STATUS WORD (00010)

MESSAGE SEQUENCE = TRANSMIT STATUS * STATUS

The status and BIT word registers are not altered by this command and contain the resulting status from the previous command.

ERROR CONDITIONS

1. Invalid Command. No response, command ignored.

2. Command Followed by Data Word. No status response. Bits set: message error (SW), High Word Count (BIT Word).

3. T/R bit Set to Zero. No status response. Bits set: message error (SW), T/R Error (BIT Word).

4. Zero T/R bit and Broadcast Address. No status response. Bits set: message error, broadcast received (SW), Illegal Mode Code, T/R

Error (BIT Word).

5. Broadcast Address. No status response. Bits set: message error, broadcast received (S/W), Illegal Mode code, T/R Error (BIT Word).

INITIATE SELF-TEST (00011)

MESSAGE SEQUENCE = SELF TEST * STATUS

The CT2553 responds with a status word. If the command was broadcast, the broadcast received bit is set and status transmission

suppressed. Short-loop test is initiated on the status word transmitted. If the test fails, an RT fail flag is generated.

ERROR CONDITIONS

1. Invalid Command. No response, command ignored.

2. Command Followed by Data Word. No status response. Bits set: message error (SW), High Word Count (BIT Word).

3. T/R bit Set to Zero. No status response. Bits set: message error (SW), T/R Error (BIT Word).

4. Zero T/R bit and Broadcast Address. No status response. Bits set: message error, broadcast received (SW), T/R Error (BIT Word).

5. Faulty Test. Bits set: terminal flag (SW), A/B Loop Test Fail, Current 1553 Bus (A or B) Loop Test Fail (BIT Word).

TRANSMITTER SHUTDOWN (00100)

MESSAGE SEQUENCE - SHUTDOWN * STATUS

This command is only used with dual redundant bus systems. The CT2553 responds

with status. At the end of the status transmission, the CT2553 inhibits any further transmission from the dual redundant channel. Once

shutdown, the transmitter can only be re-activated by Override Transmitter Shutdown or RESET RT commands.

ERROR CONDITIONS

1. Invalid Command. No response, command ignored.

2. Command Followed by Data Word. No status response. Bits set: message error (SW), High Word Count (BIT Word).

3. T/R bit Set to Zero. No status response. Bits set: message error (SW), T/R Error BIT Word).

4. Zero T/R bit and Broadcast Address. No status response. Bits set: message error, broadcast received (SW), Illegal Mode Code, T/R

Error (BIT Word).

Table 6 – Mode Codes