Rockwell Automation 1772-L8_LW_LWP_LX_LXP,D17726.5.8 User Manual - Manual (Page 251)

EAF
Process Control Instructions
Chapter 16
16-40
Rung 3 This is an unconditional File-to-Word Move instruction
containing the values for which you want to calculate the
standard deviation. Addresses 201 through 205 are
externally indexed by the counter 0034. The starting position
must be one (see rung 2).
Rung 4 This is the EAF rung.
Bit 03315 a timer done bit enabling the calculation.
(see rung 1)
Bit 04415 the result word done bit that stops the
standard deviation calculation after all five
values have been entered and their standard
deviation calculated.
Word 0032 the calculation length or the number of
samples for which you want to find the
standard deviation (five in this example).
Word 0035 the rate per scan (must be 001).
Word 0036 the Output WORD ADDR(ess) of the
File-to-Word Move instruction. It will
contain a different value each time the
instruction is enabled (every 3 seconds). The
3 Gets must be included. The first two can
reside in any storage location; the third Get
must correspond to the RESULT ADDR(ess)
of the File-to-Word move in rung 3.
The Data Address, word 047, contains the current position for which the
standard deviation is being calculated. The Result Address is the first of
six consecutive words used for intermediate calculations and for storing the
final result. The first 4 words (040-043) are reserved for intermediate
calculations. Word 044 contains the 3 most significant digits of the result
and word 045 contains the 3 least significant digits. There is an implied
decimal point between the words (044 and 045).