Front Panel Operation
2-100
2.16.3 Buffer multiple displays
Math operations performed on buffered readings are avail-
able when readings are recalled. Just press NEXT DISPLAY
to view the math operation on the bottom line of front panel
display, in the following order. Note that the appropriate data
store element has to be selected in order to get the reading.
1. RH and ET – relative humidity and external tempera-
ture, for example:
Rdg#+00000 RH=35% ET= 23°C
Note: In order to get these readings, the appropriate sen-
sor has to be connected to the Model 6517 and it has to
be enabled (see A/D-CONTROLS in paragraph 2.19.7).
2. V-Source –V-Source output, for example:
Vsource = +0001.000V
3. MAX – maximum reading in buffer, for example:
MAX=+1.00 at RDG# +00090
Notes:
A. Display response may be slow due to calculation of
statistics for large buffers.
B. Exponents are in terms of primary units of function
on top line (i.e., volts, not millivolts).
4. MIN – minimum reading in buffer, for example:
MIN=+1.00 at RDG# +00012
5. Average – This math operation displays the mean value
of the buffered readings, for example:
Average = +1.6345e+00
The equation used to calculate the mean is:
where: x
i
is a stored reading, and
n is the number of stored readings.
Note: If n = 0, the result is NAN (not a number).
6. StdDev – This operation displays the standard deviation
of the stored readings, for example:
StdDev = 1.4944e-03
y
X
i
i
1
=
n
∑
n
------------------
=
The equation used to calculate the standard deviation is:
where: x
i
is a stored reading, and
n is the number of stored readings.
Note: If n
≤
1, the result is NAN (not a number).
NOTE
These statistics are invalid if the measure-
ment function changed during data store
(e.g., when scanning different functions).
The Model 6517A uses IEEE-754 floating point format for
math calculations.
The last display in this series allows you to dump the buff-
ered readings to a printer. See paragraph 2.19.2 for details on
configuring printers.
2.17 Filters
Filtering stabilizes noisy measurements caused by noisy in-
put signals.
The Model 6517A uses two types of filters: digital and me-
dian. The displayed, stored or transmitted reading is simply
the result of the filtering processes. Note that both the digital
and median filters can be in effect at the same time.
When FILTER is enabled, the selected filter configuration
for that measurement function is in effect. Filtering is en-
abled by pressing the FILTER key (FILT annunciator turns
on). Pressing FILTER a second time disables filter.
When FILTER is enabled, the status of the two filters will be
briefly displayed. For example,
Filter Enabled
Digital = ADV(10) Median ON
The above display message indicates that the advanced filter
(average 10 readings) is in effect and the median filter is on.
If no digital filter is selected (NONE) and the median filter is
off, the message “No Filters Selected” will be displayed. In
this case, enabling FILTER has no effect on the input signal.
Filtering is performed only on primary display measure-
ments; it has no effect on multiple displays.
X
i
2
-
1
n
---
X
i
i=1
n
∑
2
i=1
n
∑
n-1
----------------------------------------------------
y =
