H A R D W A R E O P E R A T I O N
Data Device Corporation
BU-65570/2i Manual
21
frame symbols identify special operations that should be performed at
that point. For example the symbol ‘END_OF_MINOR’ specifies that the
BC must stop message processing until the minor frame time counter
expires. Then, once the timer expires, the counter is reset with the Minor
frame time, and the next message in the list will be processed.
Every frame list must have at least one entry of ‘END_OF_MAJOR’.
The minor frame time is based on a programmable 32-bit counter with 1
µ
sec resolution. The BU-65572iX supports major frames of up to 1024
messages per installed channel, with a period of up to 72 minutes.
BC Error Injection
Error conditions may be injected on a message by message basis. The
BU-65570I/72I supports three categories of injected BC Errors: length
errors, encoding errors, and gap errors. Length Errors include both word
count errors and bit count errors. Word Counts of -32 to +1 words may
be programmed. Bit counts of +3, +2, +1, -3, -2, or -1 bit may be
programmed on any word within the message.
Encoding errors are implemented though the use of two simple yet
powerful mechanisms for modifying the output of the BU-65572i's
Manchester encoder. The two modifying functions are glitch and inverse.
A glitch error will force the output of the encoder to an idle bus condition
for the specified period of time.
An inverse error will invert the output of the encoder for the specified
period of time. The word number, starting time, and width specify the
placement of the error. The error may be placed in any word within the
message and its starting time may be programmed in 500 nsec with a
width of up to 3
µ
sec. This error injection is capable of generating a host
of errors including invalid sync patterns, parity errors, and Manchester
bi-phase errors.
A gap of 3, 4, or 5
µ
sec (measured mid-parity crossing to mid-sync
crossing) may be inserted between any two words in a message. This
allows for a "dead time" gap between words of 1,
2, or 3
µ
sec.
Inserting Asynchronous Messages
The BU-65572iX allows an asynchronous message to be inserted while
the card is running. The inserted message will be executed upon
completion of the current message. The user will define all
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