H A R D W A R E O P E R A T I O N
Data Device Corporation
27
BU-65572T Manual
completion of the current message. The user may define an
asynchronous message after the END_OF_MAJOR frame symbol or
choose a message in the active frame. The message is inserted into the
running frame by calling the „ddcInsertMessage‟ routine. The hardware
does all of the work.
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.
7.2.4 BC Intermessage Routines
Upon completion of a BC message, the
BU-65572T
'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. The Tester Simulator Menu
Manual, Appendix B provides a summary of the
BU-65572T
's
intermessage routines.
Intermessage routines are also 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-65572T
, discrete signals can be set and cleared at the 40 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-65572T
.
7.2.5 Response Timeout
The
BU-65572T
BC, RT‟s and MT support programmable response
timeout values ranging from 2 to 29 secs in 1-µsec increments.
7.3 RT Mode
The
BU-65572T
can simultaneously simulate the operation of 31 unique
remote terminals (RTs) plus a broadcast address for each of the installed
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