Sequoia / Tahoe Series User Manual California Instruments
M447352-01 REV-A 299
9. Send the SCPI command, INST:NSEL 3, and repeat Step-7 to align Phase-C.
10. Repeat Step-7 for sync frequencies in the unit of 100 Hz, 200 Hz, 550 Hz, 819 Hz, and 905 Hz
(with SCPI command, SYNC:FREQ <n>), or the highest frequency of the particular power source
model being aligned.
11. The calibration coefficients could be verified with the SCPI query, CAL:PHASE?. First cycle the
AC input power off then on, and then send the command, CAL:PHASE?. The command will
return a command-separated number sequence of calibration coefficients with the following
format: f1,data1,f2,data2,f3,data3,f4,data4,f5,data5,f6,data6,current-cal.
9.3.9 Alignment of External Programming Signal for Output Current Amplitude, DC Output
The external analog programming signals for setting the output current (RPV) are available in the External
Input/Output Control connector: Phase-A signal input at Pin-1; Phase-B signal input at Pin-2; Phase-C
signal input at Pin-3; signal return at Pin-4 (refer to Section 3.8.4). The alignment is performed with a DC
input: for example, a 0-10 VDC signal would produce a DC output current that would vary from zero to full-
scale of the selected output current range.
1. Connect the signal inputs for Phase-A (Pin-1), Phase-B (Pin-2), and Phase-C (Pin-3) together for
connection to the same function generator output in Step-2.
2. Connect a DC reference voltage to the external analog programming connector in Pin-1, Pin-2,
and Pin-3 (signal), and Pin-4 (signal return); refer to Section 3.8.4.
3. Set Voltage Source (connected at SQ unit load side) Mode DC, voltage to 200V, and current limit
Max (should be greater than the SQ unit).
4. Send the following SCPI commands to the power source (220 VDC range selected; ALC is off;
do not turn on the output at this time):
INST:COUP ALL
OUTP 0
MODE DC
VOLT:RANG 220
CURR:ALC OFF
SYNC:VOLT 200
CURR:REF RPV
5. Perform the synchronization procedure section 9.3.3 and enable the output of Sequoia unit using
command OUTP 1.
6. Enter the calibration password with the SCPI command, CAL:PASS “5000”.
7. DC Offset alignment, low-range DC output (220 VDC):
8. Send the SCPI command, INST:NSEL 1, to select Phase-A.
9. Perform the DC offset alignment for the selected phase with the SCPI command,
CAL:MEAS:EXT:OFFS:DC 0, with the output off and the external analog input at 0 VDC. Send
the SCPI query command, *OPC?, to determine when this alignment step has been completed;
the query will return a 1 to indicate completion. Ensure alignment has been completed (query
returns a 1) before continuing.
10. Send the SCPI command, INST:NSEL 2, and repeat Step-7 to align Phase-B.
11. Send the SCPI command, INST:NSEL 3, and repeat Step-7 to align Phase-C.
12. DC Gain alignment, high-range DC output (220 VDC):
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