Rockwell Automation 1771-PD PID MODULE (+DU) - Manual (Page 76)

Programming
Chapter 3
3Ć33
W34(W54) Feedforward Gain, K F. (XF) This word contains the
feedforward gain constant for the loop. Data format is 4-digit BCD
(99.99 dimensionless with implied decimal point. Multiplier bits B07,
B06 in word W30(W50) can be selected for x1, divided by 10, x10, 1100
(Table 3.F). The range can be 0.000 to 9999 when using the multipliers.
W35(W55) Lead Time Constant, TB. (XF) This word contains the lead
time constant for the loop. The lead/lag feature is selected by bit B05 in
word W30(W50). To disable the lead portion of the filter, reset TB to
zero. Data format is 4-digit BCD (99.99 in units of seconds) with implied
decimal point. By using the x10 multiplier bit B11 in word W19(W39),
the range can be 00.00 to 999.9.
W36(W56) Lag Time Constant, TC. (XF) This word contains the lag
time constant for the loop. The lead/lag feature is selected by bit B05 in
word W30(W50). To disable the lag portion of the algorithm, reset TC to
zero. Data format is 4-digit BCD (99.99 in units of seconds) with implied
decimal point. By using the x10 multiplier bit B10 in word W19(W39),
the range can be 00.00 to 999.9.
NOTE: There is no word number 37 to program. By omitting W37, the
storage words for loop 1 and loop 2 parameters are exactly 20 counts
apart.
Example: W20 Integral Gain 1 (W40 Integral Gain 2)
Status Block: W57ĆW74
The status block is a read block transfer file of up to 18 words which is
used to report loop status, alarm and diagnostic information and to prompt
the proper block transfer sequences.
Only words W57 through W67 will be read if the module is selected for
loop 1 operation. The entire block (words W57 through W74) is read if
the module is selected for two-loop operation.
The 18 words that comprise the status block are defined in the paragraphs
that follow. Table 3.G lists the status block words. All the words of the
dynamic block, loop block and status block are listed in Table 3.J, in
Figure 3.13 and Figure 3.14 found at the end of section titled Word and
Bit Definitions.