Spectracom GSG-5 series, User Manual With Scpi Manual

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Command Syntax
SOURce:SCENario:ADVLOG? <logID>[,<filter1>,<filter2>,...,
<filterN>]
<logID>
– log identifier that specifies what log data to request
<filterX>
– optional filter expression that allows to include into response only specified
record types
Mechanism
When a scenario is running, the GSG unit internally creates log records at predefined time
intervals and puts them into a limited-size queue with a FIFO (First In – First Out) structure where
they remain for some time (several seconds). As the scenario continues to run, new records get
added into the log and old records get removed either automatically or by request from the
user. Each type of log features its own (independent) queue.
RSG log records are created every 100 ms. SAT log records are created every 1 second.
When requested using the
sour:scen:advlog?
command, log records are removed from
the queue starting with the oldest available records. They are returned as text lines containing
comma-separated fields. These lines can be easily processed by user-developed software to
extract specific fields, or they can be stored in a csv- file allowing for further analysis with
spreadsheet software.
When the user does not request any log records, the latest log records remain in their queues
until the unit is requested to start a new scenario. Hence it is possible to get remaining records
even after a scenario was stopped.
One possible approach to using the advanced log feature is to periodically make a series of
repetitive queries, waiting for an empty response in each series. An empty response signifies
that the most recent data have been received and no new data is available so far.
General response structure
A response to an advanced log command usually contains several lines of text, with each line
containing several comma- separated fields. The order of these fields corresponds with the
labels order in response to a
SOURce:SCENario:ADVLOG:HEADER?
query.
Each line of the response is terminated with the line end symbol “
\n
” (ASCII code 0x0A). Not
all records may be returned at once, so another request may be required. If all records have
been returned and no new records are available, an empty response will be returned. When
SCPI raw mode is enabled, responses are additionally terminated with an empty line (con
taining only the newline symbol in it), even if no new records are available. The additional
newline symbol is intended to simplify end of response detection on the TCP client side.
Since queue sizes are limited, it may be important to ensure that no record is missed due to
queue overflow caused by too low a query rate. Log records of RSG and SAT logs contain the
id
field that can be used to detect such an “overflow condition”. The
id
field is a 16- bit
unsigned counter that counts from 0 to 65535 and then wraps to 0.
Note that several consecutive lines may contain the same
id
field. That is because a group of
records is usually created at the same moment, but may still contain different data sets. For
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User Manual GSG-5/6 Series Rev. 26
6.3 Command Reference