Rockwell Automation 1772-LV Mini-PLC - 2/15 Programmable Controller (Series B) Programming and Operations - Manual (Page 177)

Quick Reference Section
Appendix A
AĆ8
Table A.E
Conter Instructions
NOTE: The counter word address, XXX, is assigned to the counter accumulated areas of the data table To determine which addresses are valid
accumulated areas, the most significant digit in the word address must be an even number.
Bit 14 is the overflow/underflow bit.
BIt 15 is the count complete bit.
BIt 16 is the enable bit the for CTD instruction.
Bit 17 is the enable bit for the CTU instruction.
The word address displayed will be 3 or 4 digits long depending on the data table size. WHen entering the word address, use a leading zero if
necessary.
Key Symbol Instruction Name 1770-T3 Display Rung Condition Status Bit
-(CTU)- Up Counter XXX
-(CTU)-
PR YYY
AC ZZZ
Each time the rung goes true, the
accumulated value is incremented one
count. The counter will continue counting
after the preset value is reached.
The accumulated value can be reset by the
CTR instruction
When the rung is true:
BIt 14 -= set if AC>999
Bit 15 - set when AC ≥ PR
Bit 17 - set
When the rung is false:
Bit 14 and 15 - retained if it ws set
BIt 17 - reset
-(CTR)- Counter Reset XXX
-(CTR)-
PR YYY
AC ZZZ
XXX - Word address of the CTU is resetting
The preset and accumulated values are
automatically entered by the industrial
terminal.
When the rung is ture, the CTU, or CTD
accumulated value and status bits are reset
to 000.
When the rung is true:
Bit 14, 15, 16, 17 - reset
When the rung is false:
No action is taken.
-(CTD)- Down Counter XXX
-(CTD)-
PR YYY
AC ZZZ
Each time the rung goes true, the
accumulated value is decreased by one
count.
When the rung is true:
Bit 14 - set when AC <000
Bit 15 - set when AC
Bit 16 - set
When the rung is false:
Bit 154 and 15 - retained if it was set
Bit 16 - reset