CT2565 Datasheet, PDF (7/31 Pages) Aeroflex Circuit Technology – CT2565 Bus Controller, Remote Terminal and BUS Monitor FOR MIL-STD-1553B

TRANSFER/CONDITION
DESCRIPTION
ERROR SIGNAL PIN
CONTROL/COMMAND WORD 1
Memory read by BC subsystem.
Handshake Failure
No response to Bus Request within timeout BC waits for Grant
-
period.
(no 1553 timing error)
LOOPED WORD
Short Loop Failure
Long Loop Failure
Looped back through receiver.
Received Word ≠ last xmitted word.
LOOPERR
46
DMA/Write looped word to subsystem.
User Defined
-
RT-RT
Status-RT1, data, status-RT2 response
(See definitions in
to follow receive, transmit, commands.
STATUS/DATA WORD
-
below)
STATUS WORD
No Status Received within 15.5µS NODT timeout
TIMEOUT
4
EOM
57
RT Address Mismatch
Command RTU Address ≠ Status Word
STATERR
68
RTU Address
Error Flag(s) Set
Status Word Response from RT:
STATERR
68
Error Condition
Broadcast Received bit Set
Response to Transmit Status Word mode
Broadcast Mask not set
command may allow this, all others ERROR. (See BC Control Word)
68
STATERR
DATA WORD
Handshake Failure
Transmit Command
Receive Command
No subsystem response to Bus Request.
BC waits for Grant.
Data lost: Word Count fails.
MSGERR
30
1553 transmission gap.
Status Word response:
STATERR
68
Data Received from RTU
Less than word count
Greater than word count
Transmit Command (RTU response)
MSGERR and EOM
4
More data received than requested.
MSGERR and EOM
30
Data after Status Set
(all extra words)
Transmit Command: data words received
after status to subsystem.
DMA/memory write
(for each)
-
FORMAT ERROR
-
MSGERR
30
Notes:
(1) LOOPERR is a .5µS pulse which occurs near DMA handshake for loop back word.
(2) TIMEOUT is a 40/160nS pulse which occurs 19.5µS ±0.5µS after the mid-bit parity of the last word onto the bus.
(3) STATERR is a 120/166nS pulse which occurs during the status word DMA handshake.
(4) MSGRR is a 40/160nS pulse which occurs approximately 100nS before INCMD goes high. It is triggered by NODT going inactive (i.e.,
low word count).
Table 4 – BC Error Handling
RTU Response
The addressed RTU(s) must respond (to
non-broadcast commands) within a timeout
period as shown in Figures 7, 8, and 9. Figures
10 and 11 illustrate the BC Mode Code Timing.
Status and data words received from the 1553
port are transferred to the subsystem via a
handshake and memory write operation for each
(See Message Length Checking).
BC Status/Error Handling
Message transfer errors are indicated using the
TIMEOUT, MSGERR, LOOPERR and STATERR
BC status outputs (pins 4, 30, 46 and 68
respectively). Additional error detection
methods include user evaluation of status, data
and (long) loop words and/or use of the 1553B
dual redundant mode codes. Note that certain
error conditions not reflected in the current
Status Word (SW) can occur; Broadcast CMD
RT-status and post RT status response may be
accessed via the Transmit Status Word mode
command.
Transmit Bit Word. Additional status informa
tion is generated by an RTU (CT2565 for each
transfer in the form of a BIT word). This word
may be accessed by the BC using the
TRANSMIT B-I-T WORD mode command. See
RTU Error Handling and Mode Code sections).
Message Length Checking. The BC stores the
command word, word-count field in an internal
register. By decrementing this register following
each data word transfer (See BC Memory
Read/Write Timing), the BC can detect an
incorrect message length.
For a description of the possible BC error,
indicators occurring during each stage of
message transfer read from left to right in
Table 4. For a description of the possible causes
of errors within a transfer, read from right to left.
Aeroflex Circuit Technology
7
SCDCT2565 REV B 8/10/99 Plainview NY [phone]