Hi Geoff,
Thanks so much for your help. I had multiple contacts with the company and eventually figured out the problem: basically, commands using ':MEAS:FREQ?' or 'CONFIGURE' can do a good job in single reading, but too much time-consuming for continuous reading. A solution to fast continuous reading is to use what is called 'running mode' (pls also refer to the 'to optimize throughput' example in the programming guide of this counter). Detailed solution is as follows (notes go after '//'):
1. Initialize the counter with 'VISA write':
*RST;
*CLS;
*SRE 0;
*ESE 0;
:STAT:PRES;
:EVEN1:LEV:AUTO OFF;LEV:REL 50;HYST:REL 100;SLOP POS;
:INP1:IMP 50;COUP AC;ATT 1;FILT ON;
:ROSC:SOUR INT; //use internal oscillator
:ROSC:EXT:CHEC OFF;
*DDT #15FETC?; //define trigger mode
:DIAG:CAL:INT:AUTO OFF;
:DISP:ENABLE OFF;
:HCOPY:CONT OFF;
:CALC:MATH:STATE OFF;
CALC2:LIM:STATE OFF;
:CALC3:AVER:STATE OFF;
FREQ:ARM:SOUR IMM;
:FREQ:ARM:STOP:SOUR TIM;
:FREQ:ARM:STOP:TIM 0.07S; //gating time=0.07s; the longer gating time is, the better frequency precision will be, but the longer measuring time will be (that is, time resolution becomes worse);
:FREQ:EXP 6MHz;
:INIT:CONT ON; //use continuous mode or 'running' mode
2. Use the following in For-loop for multiple measurements using 'VISA write':
:FETC:FREQ?
Then, use 'VISA read' right after the above command to read buffer
In my measurement, 0.07s gating time gives a precision better than 0.01Hz, and ~13 readings in 1 second.
Regards,
Yuanxia