Stanford Research Systems SIM918, Руководство по эксплуатации и обслуживанию

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3 – 14 Remote Operation
Autozero Phase PHAS?
Query the autozero switch position in the preamplifier. The re-
sponses are
ZA 0
(while zeroing the input voltage of the main am-
plifier itself) and
ZZ 1
(while zeroing the o
ff
set volage of the zeroing
amplifier). These responses alternate with every cycle of the refer-
ence clock.
The switches are parked in the
ZA
state when autozero is o
ff
.
TOKN ON; PHAS?
Example:
ZZ
Keep PLL Active APLL(?) { z }
Set (query) the “keep PLL active when autozero is o
ff
” mode of
the preamplifier { to z
=
( OFF 0 ,
ON 1
) } .
This setting only applies to the external reference clock direction.
When
APLL is
OFF
, turning o
ff
the autozero function ( CHOP
OFF
)
will fully halt the PLL oscillator (Section 2.5), ensuring that no digital
clock transitions occur. One consequence of APLL
OFF
is that the
oscillator will require up to 250 s to reestablish the lock to an external
reference when returning to
CHOP
ON
.
Conversely, with APLL ON the internal oscillator will continue to track
an external 1 pps reference clock during CHOP
OFF
periods. In this
case, there is no re-lock time needed when returning to CHOP
ON
.
The PLL oscillator always turns o
ff
with CHOP OFF in the internal
reference clock mode.
The
APLL
setting is retained in non-volatile memory, and is not mod-
ified by a power-on reset.
APLL 1
Example:
3.4.6 Calibration commands
Autocalibration ACAL
Perform a self-calibration (Section 2.6).
Make sure to disconnect all
inputs and outputs to the SIM918. Remote commands are not processed
until ACAL is complete.
ACAL Example:
LDDE?
0
checks for success of an autocalibration.
SIM918 Precision Current Preamplifier