H A R D W A R E O P E R A T I O N
Data Device Corporation
BU-65570/2i Manual
22
asynchronous messages after the END_OF_MAJOR frame symbol and
insert the message into the running frame by calling the insert message
routine. The hardware does all of the work.
Once the frame has been defined and the BC is running, asynchronous
messages may be inserted at any time by asserting the
‘ddcInsertMessage’ (see BU-69068 manual) routine. This routine
specifies which 1553 device the operation should be processed by, and
the message index in the frame list that should be inserted. The
asynchronous message will be inserted immediately following the
present message.
It should be noted that if enough messages are inserted into a minor
frame, the messages could overrun the minor frame time. In this case,
all of the messages will be processed, and the first message of the next
minor frame will occur immediately.
BC Intermessage Routines
Upon completion of a BC message, the BU-65572i''s on-board
processor will execute up to 2 intermessage routines. Intermessage
routines are used to implement automatic retries on failed messages as
well as other “end of message” functions.
Intermessage routines are used to signal the user application that an
interrupt has been generated. This can occur at the end of a message
for BC operation, when a data table has been accessed in RT operation,
or when the Monitor stack is 1/3 full.
Another use of intermessage routines is to signal external hardware that
a specific event occurred. As messages are being processed by the
BU-65572iX, discrete signals can be set and cleared at the 25 pin ‘D’
connector. These discretes can be used to synchronize an oscilloscope
or other external device.
There are also intermessage routines that will listen at the ‘D’ connector
for inputs that can be used to initiate operations in the BU-65572iX.
Response Timeout
The BU-65572iX BC RT’s and MT support programmable response
timeout values ranging from 2 to 29
µ
secs in 1-µsec increments.
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
