BU-61582 データシートの表示（PDF） - Unspecified
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BU-61582 Datasheet PDF : 48 Pages
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PROGRAMMABLE BUSY
As a means of providing compliance with Notice 2 of MIL-STD-
1553B, the BU-61582 RT provides a software controllable
means for setting the Busy Status Word bit as a function of sub-
address. By a Busy Lookup Table in the BU-61582 address
space, it is possible to set the Busy bit based on command
broadcast/own address, T/R bit, and subaddress. Another pro-
grammable option allows received Data Words to be either
stored or not stored for messages when the Busy bit is set.
OTHER RT FUNCTIONS
The BU-61582 allows the hardwired RT Address to be read by
the host processor. Also, there are options for the RT FLAG
Status Word bit to be set under software control and/or automat-
ically following a failure of the loopback self-test. Other software
controllable RT options include software programmable RT
Status and RT BIT words, automatic clearing of the Service
Request Status Word bit following a Transmit Vector Word mode
command, capabilities to clear and/or load the Time Tag Register
following receipt of Synchronize mode commands, options
regarding Data Word transfers for the Busy and/or Message
Error (Illegal) Status Word bits, and for handling of 1553A and
reserved mode codes.
MONITOR (MT) ARCHITECTURE
The BU-61582 provides three bus monitor (MT) modes:
(1) The “AIM-HY” (default) or “AIM-HY’er” Word Monitor mode.
(2) A Selective Message Monitor mode.
(3) A Simultaneous Remote Terminal/Selective Message Monitor
mode.
The strong recommendation for new applications is the use of
the Selective Message Monitor, rather than the Word Monitor.
Besides providing monitor filtering based on RT Address,T/R bit,
and Subaddress, the Message Monitor eliminates the need to
determine the start and end of messages by software. The devel-
opment of such software tends to be a tedious task. Moreover, at
run time, it tends to entail a high degree of CPU overhead.
WORD MONITOR
In the Word Monitor mode, the BU-61582 monitors both 1553
buses. After initializing the Word Monitor and putting it on-line
the BU-61582 stores all Command, Status, and Data Words
received from both buses. For each word received from either
bus, the BU-61582 stores a pair of words in RAM. The first word
is the 16 bits of data from the received word. The second word is
the Monitor Identification (ID), or “Tag” word. The ID Word con-
tains information relating to bus channel, sync type, word validi-
ty, and interword time gaps. The BU-61582 stores data and ID
words in a circular buffer in the shared RAM address space.
TABLE 25 shows the bit mapping for the Monitor ID word.
MONITOR TRIGGER WORD
There is a Trigger Word Register that provides additional flexi-
bility for the Word Monitor mode. The BU-61582 stores the value
of the 16-bit Trigger Word in the MT Trigger Word Register. The
contents of this register represent the value of the Trigger
Command Word. The BU-61582 has programmable options to
start or stop the Word Monitor, and/or to issue an interrupt
request following receipt of the Trigger Command Word from the
1553 bus.
SELECTIVE MESSAGE MONITOR MODE
The BU-61582 Selective Message Monitor provides features to
greatly reduce the software and processing burden of the host
CPU. The Selective Message Monitor implements selective mon-
itoring of messages from a dual 1553 bus, with the monitor fil-
tering based on the RT Address, T/R bit, and Subaddress fields
of received 1553 Command Words. The Selective Message
Monitor mode greatly simplifies the host processor software by
distinguishing between Command and Status Words. The
Selective Message Monitor maintains two stacks in the
BU-61582 RAM: a Command Stack and a Data Stack.
SIMULTANEOUS RT/MESSAGE MONITOR MODE
The Selective Message Monitor may function as a purely passive
monitor or may be programmed to function as a simultaneous
RT/Monitor. The RT/Monitor mode provides complete Remote
Terminal (RT) operation for the BU-61582’s strapped RT address
and bus monitor capability for the other 30 non-broadcast RT
addresses. This allows the BU-61582 to simultaneously operate
as a full function RT and “snoop” on all or a subset of the bus
activity involving the other RTs on a bus. This type of operation
is sometimes needed to implement a backup bus controller. The
combined RT/Selective Monitor maintains three stack areas in
the BU-61582 address space: an RT Command Stack, a Monitor
Command Stack, and a Monitor Data Stack. The pointers for the
various stacks have fixed locations in the BU-61582 address
space.
SELECTIVE MESSAGE MONITOR MEMORY
ORGANIZATION
TABLE 32 illustrates a typical memory map for the SP’ACE in the
Selective Message Monitor mode. This mode of operation
defines several fixed locations in the RAM. These locations allo-
cate in a manner that is compatible with the combined
RT/Selective Message Monitor mode. The fixed memory map
consists of two Monitor Command Stack Pointers (location 102h
and 106h), two Monitor Data Stack Pointers (locations 103h and
107h), and a Selective Message Monitor Lookup Table (0280-
02FFh) based on RT Address T/R, and subaddress. Assume a
Monitor Command Stack size of 1K words, and a Monitor Data
Stack size of 4K words.
Data Device Corporation
www.ddc-web.com
21
BU-61582
M-08/04-0
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