Rockwell Automation 1771-PD PID MODULE (+DU) - Manual (Page 195)

Application Example 2, Periodic Block
Transfer
Appendix C
CĆ11
rung 13* The read block transfer instruction reads the next block of
data sent by the PID module and transfers it to the buffer
area of the data table, words 233-2568. This rung is
executed only when bit 050/01 is high (refer to the
explanation for rung 8) or when storage bit 050/07 is high
(refer to explanations for rung 9 thru 11).
rung 14* Upon completion of a valid read block transfer
(determined by examining the block transfer done bit
113/07), the data from the input buffer is transferred to the
status block data table words 347-3708. Identifier bits 16
and 17 of word 2348 are examined for a low logic state to
ensure that the input buffer had received valid status data
from the PID module.
rung 15 Timer 0438 is the read block transfer watchdog timer. It
will begin timing whenever the read block transfer done bit
113/07 is low. Upon completion of a valid read block
transfer, the done bit goes high and resets the timer. The
preset value of this timer is user-selectable.
rung 16 Annunicator lamp 012/02 illuminated when the read block
transfer watchdog timer times out.
rung 17 Annunciator lamp 012/04 illuminates when the manual
control station is in manual mode.
rung 18
thru 20*
These rungs reset bit 050/01 upon completion of a
successful load/enter sequence. Bit 353/12 is the
load/enter complete bit. Bit 050/02 is a storage bit which
allows 353/12 to toggle from 0 to 1 before resetting050/01.
rung 21* The load bit 257/06 is latched when storage bit 050/01 is
high. Bit 050/01 is high. Bit 050/01 is high during a
load/enter sequence.
rung 22 The MODULE NOT INITIALIZED indicator 012/03
illuminates when the power-up bit 350/13 is high or the
power-up complete bit 353/04 is low.
rung 23* Ready bit 350/12 resets the load bit 257/06.