Most
main functions have a short form of header which may
be
used for clarity and brevity
in
simple messages, for example:
CRFQ 1.25 GHZ is the same as CRFQ:VALUE 1.25GHZ
Program
data
Data can take many forms, as follows:
Decimal Numeric Data is a flexible numeric format which encompasses
integer, fixed
point and floating point
(mantissa
and exponent)
representations. Data is rounded to a resolution
appropriate to the function. Decimal data can, in most cases, be followed by the appropriate
units. If no units are present, the specified default units are assumed.
Character Data is an alphanumeric word.
String Data consists of a number of 7-bit ASCII characters enclosed in quotes, either a
pair of single ('ASCII 39') or double ("ASCII 34") quotes may be used.
Block Data is used by *PUD and allows a number of 8-bit bytes to be transferred.
For
further information see the Service Manual.
Some commands can accept Multiple Data items which are separated
by commas, for
example
MODE FM,AM.
Message exchange protocol
The controller should not attempt
to read a response
until
it has sent
the entire query
message (terminated
by EOM). Also,
it
should not
start to send a new
message until it has read
the entire response (terminated by EOM). The
query
message may contain
more than one
query
message
unit,
but
only one response message (containing
several
response message units) is
generated.
Failure to follow the protocol will generate a query error:
UNTERMINATED (error
116)
occurs when the controller attempts to read a response
without
having
sent a query.
INTERRUPTED (error
117)
occurs when the
controller
starts to send
a
new
message
before having read
the response to a preceding query.
DEADLOCK (error
118)
can only occur if the input and output buffers are both filled by
the controller having sent an extra long Message containing several query
message
units.
The 2040 series have input buffer stores of 256 characters and an output buffer of two
response message units.
Remote/local operation
When the 2040 series Signal Generator is addressed by the controller it will enter its remote
mode and the screen will have only one key legend, [LOCAL]. Pressing this key
returns the unit
to normal manual operation,
unless Local Lockout has been asserted by the controller.
46882-074C
3-2-5
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