Tektronix PFG 5105, Instruction Manual

Page: 72 / 89

(
abbreviated version must be those given in the full­
length version. For documentation of programs, the
user may add alpha characters to the full-length
version. Alpha characters may also be added to a
query header, provided the question mark is at the
end.
USER?
USERE?
USEREQ?
Multiple arguments are separated by a comma.
2,3
2,sP3
NOTE
In the last example, the space is treated
as a
format character because it follows the comma
(the argument delimiter).
Number Formats
The instrument accepts the following kinds of numbers
for any of the numeric arguments.
NR1
Signed or unsigned integers (including +0
and -O). Unsigned integers are Jnterpreted
as positive.
NR2
NR3
Examples: + 1, 2, -1, -10.
Signed or unsigned decimal numbers. Un­
signed decimal numbers are interpreted as
positive.
Examples: -3.2, + 5.0, 1.2
Floating point numbers expressed in scien­
tific notation.
Examples: + 1.0E-2, 1.0E2, 1.E-2, 0.01 E + O
Link arguments can be used in place of
scientific notation.
Examples: + 10:MHZ, -.25:V, 2:KHZ.
Rounding of Numeric Arguments
The instrument rounds numeric arguments to the
nearest unit of resolution and then checks for out-of­
range conditions.
PFG 5105/5505 Instruction Manual
Programming
Message Protocol
Upon receipt by the instrument, a message is stored
in the Input Buffer, then processed, and executed.
Processing a message consists of decoding com­
mands, detecting delimiters, and checking syntax. For
setting commands, the instrument then stores the
indicated changes in the Pending Settings Buffer. If
an error is detected during processing, the instrument
asserts SRQ, ignores the remainder of the message,
and resets the Pending Settings Buffer. Resetting the
Pending Settings Buffer avoids undesirable states that
could occur if some setting commands are executed
while others in the same message are not.
Executing a message consists of performing the
actions specified by its command(s). For setting
commands, this involves updating the instrument set­
tings and recording these updates in the Current
Settings Buffer. The setting commands are executed
in groups -that is, a series of setting commands is
processed and recorded in the Pending Settings Buffer
before execution takes place. This allows the user to
specify a new instrument state without having to
consider whether a particular sequence would be
valid. Normally, execution of the settings occurs when
the instrument processes the message terminator,
query-output command, or an operational command
in a message. The normal execution of settings is
modified by the Device Trigger (DT) setting command.
When the instrument processes a
query-outpl/t com­
mand in a message, it executes any preceding setting
commands to update the state of the instrument. It
then executes the query-output command by retrieving
the appropriate information and putting it in the Output
Buffer. Processing and execution then continue for
the remainder of the message. The data are sent to
the controller when the instrument is made a talker.
When the instrument processes an operational com­
mand in a message, it executes any preceding
setting commands before executing the operational
command.
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