Remote Programming - Buffer; Buffer Commands - Keithley 2750 User Manual

6-8 Buffer
Standard deviation
This mode displays the standard deviation of buffered readings. The following equation is
used to calculate standard deviation:
y =
where:
NOTE
Remote programming — buffer
NOTE

Buffer commands

NOTE
The commands to perform buffer operations are listed in
mands follow the table.
2
n n
⎛ ⎛ ⎞
⎜ ⎜ ⎟
1
∑ ∑
2
-- -
X – X
⎜ ⎜ ⎟
i i
n
⎝ ⎝ ⎠
i = n 1 – i = 1
-------------------------------------------------------------- -
n 1 –
y is the standard deviation.
X is a stored reading.
i
n is the number of stored readings.
If the standard deviation calculation is being performed on a buffer that has
more than 1000 readings, the "CALCULATING" message will flash to indicate
that the Model 2750 is busy. While busy with the calculation, front panel keys
will not operate.
When readings are stored in the buffer by the TRACe command (or by front
panel data store operation), INIT and multi-sample READ? queries are locked
out. With readings in the buffer that were stored in that manner, you cannot use
the INIT or READ? command if sample count is >1 (error -225, out of memory).
The measurement event register can be read to check when the buffer becomes
H , I , or full. Status registers are covered in
When measurements are performed, the readings are fed to other enabled oper-
ations, including the Buffer.
tion)" and the commands used to read the buffer and buffer statistics.
Model 2750 Multimeter/Switch System User's Manual
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⎟
⎟
⎠
Appendix D explains
Section 11.
"Data flow (remote opera-
Table 6-1. Details on these com-
G ,