Black Box 945 - Manual (Page 24)

24
WATLOW Series 945 How to Use Data Communications
Chart & SPC
NOTE:
The time is printed
every 5th interval
(Int). The tempera-
ture variable (*) is
printed every 10th
interval.
One Int = 6 seconds.
Figure 12 -
Chart and SPC
Printout Example
100 ° F 125 75
PROCESS DATE: 01-01-90
*
*
*
*
*
*
CPKL = 1.36 CPKU = 1.32
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
U
U
U
U
U
U
U
U
U
U
U
U
U
U
U
U
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
*
*
*
* *
*
*
*
*
*
*
*
*
*
*
*
*
*
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
*
*
*
*
*
*
*
*
*
*
*
101
100
99
101
(SPCA & SPCd only) (SPCA & SPCd only)
Set Point
Temperature
01:00:01
01:00:31
01:01:01
01:01:31
01:02:01
01:02:31
01:03:01
01:03:31
Time
Lower Control Limit
(SPCA & SPCd only) Upper Control Limit
(SPCA & SPCd only)
Set Point Variable
Temperature Variable
90
92
110
110
Maximum Excursion Maximum Excursion
CP = 1.34
(Any messages concerning tchanges
in he system are printed here)
Temperature Variable
Chart and SPC Printout
Example: Log = SPCA, Int = 0.1
P = Process
S = Set Points
The Chart and SPC (Statistical Process Control) format are very similar. The only
difference is the SPC output displays the lower (L) and upper (U) control limit.
They are calculated based upon the mean value of the process variable, and are
derived from 30 random samples taken over the selected time base (tbS), the
mean value used is from the previous timebase samples (ex. the mean from the
first 30 samples is used to compute the control limits for the second 30 samples
and so on for every sample period. If SPCA (Specification limits Absolute or SPCd
(spec. limits Deviation) is selected then the CPKL, CP, or CPKu values will also be
printed. If the variation in the process value is too small to calculate the control
limits, L and U and the message "Variation Insignificant" are printed. If at any time
the process value exceeds the control limits during a print interval, the maximum
process excursion value will be printed (if both L and U are exceeded, both maxi-
mum values will be printed) on the next line printed. At any time the control limits
can be locked in by setting CLUP to "no" . If CLUP = no, new control limits can be
set by CLUP = YEs.
(Any messages concerning changes
in the system are printed here)