X
X
L
L
D
D
C
C
M
M
A
A
N
N
.
.
d
d
o
o
c
c
3
3
-
-
5
5
5
5
R
R
E
E
V
V
E
E
<INTERVAL>
= measurement interval in seconds, a decimal integer in the range
of 1 to 100000 (this field is not sent if the mode is OFF or
QUERY)
To configure Function F29, send a string in this format:
F29<SEP><MODE><SEP><FREQ><SEP><INTERVAL><CR>
If the MODE being set is OFF, then the Serial Port will respond with:
OK<CR><LF>
Otherwise, the Serial Port will respond with:
F29<SEP><TIMESTAMP><SEP><MODE><SEP><FREQ><SEP><INTERVAL><CR><LF>
where:
<TIMESTAMP>
= dayofyear:hours:minutes:seconds.subseconds in this
fixed field format: ddd:hh:mm:ss.nnnnnnnnn
This timestamp is the initial phase timestamp which will be used to compute the first fractional
frequency offset measurement which will follow either from a QUERY or PERIODIC update.
In the PERIODIC mode of operation, measurements are continually output at the specified
measurement interval until a CTRL-C character (Hex 03) is received. Reception of the CTRL-C
character automatically sets the F29 mode to OFF. In PERIODIC mode, all characters sent to the XL-
DC will be ignored until a CTRL-C is received. This mode is suitable for long term automated
observation of the performance of an external frequency standard or for the calibration of free running
timebase oscillators.
In the QUERY mode of operation, a measurement is computed and output each time that this string is
received:
F29<SEP>F<CR>
where:
F
=
ASCII character F
In this mode, the measurement interval is the time in integer seconds between receptions of the above
string. This mode is useful in matching the data rate of some other process which is concurrently being
logged and is not necessarily periodic or synchronized with the XL-DC.
The measurement returned in either the QUERY or PERIODIC modes is sent in this format:
F29<SEP><TIMESTAMP><SEP><FFO><CR><LF>
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