Allen-Bradley 2080-OB4 - Chapter 5: DeviceNet Plug-in - 2080-DNET20

Rockwell Automation Publication 2080-UM004C-EN-E - March 2015 31
High Speed Counter – 2080-MOT-HSC Appendix 4
Down Counting
Z Input (Gate) Function/Touch Probe
This signal functionality supports:
• Tou c h Pr o b e the present count value on the rising edge of IntZ_n to the
HSC_Touch Probe term in the backplane input file.
• Hold the counter at its present count value while IntZ_n = 1,
• Reset the present count value on rising edge of IntZ_n.
Ring or Linear Counter
The counter may be configured with the RingOrLinearCnt_n control bit to
rollover at its limits (ring counter) or to stop counting and set a flag (linear
counter).
0: ring counter. When the counter is a ring counter and the present count value
is equal to MaxCountValue_n, the next input count in the up direction will cause
the PresentCount_n to become the MinCountValue_n. This action is known as
rollover. And the CountOverflow_n flag will be set to indicate that a rollover has
happened. It is reset using the ResetCountOverflow bit.
Conversely, when the PresentCount_n is equal to MinCountValue_n the next
input count in the down direction will cause the PresentCount_n to become the
MaxCountValue_n. This action is known as rollunder. The CountUnderflow_n
INPUT A
INPUT B
INPUT Z
Decrement Pulse
(count down)
Decrement Pulse
(count down)
Encoder or Sensor
Encoder or Sensor
-1
-2
-3
-4
-5
-6 -7
-8
-1
-2
-3
-4
-5
-6
-7
-8
Counter 0
(Input A)
PresentCount 1
Counter 0
(Input B)
PresentCount 2
IMPORTANT
If the module gets two or more Z pulses during a single plug-in scan the
HSC_TouchProbe will be overwritten with the last stored value. There
will be no indication that more than one store has occurred.