Rockwell Automation 1756-HSC ControlLogix High Speed Counter Module - Manual (Page 36)

Rockwell Automation Publication 1756-UM007C-EN-P - November 2011
36 Frequency Modes
Period Rate /Continuous
Rate Output Examples
The following square waves illustrate the difference between Period Rate and
Continuous Rate frequency operational modes. All square waves were initiated
by applying a 50 Hz signal at the Input Z terminal of a counter configured for
either Period Rate or Continuous Rate. The output configuration remained
constant with an On value of 20,000 counts and an Off value of 80,001 counts.
Only the Scaler mode was varied to show the operation of the two modes.
Outputs in Period Rate and Continuous Rate with Scaler = 1
50 Hz at Z-Input
50% Duty Cycle
Scaler Tag= 1 Counter
Idle
Counter Times
Width of Pulse
4 MHz Count in Present Value Tag = 40,000
Output State in Period Rate
4 MHz Count = 40,000
Scaler Tag = 1
Output OnValue Tag = 20,000
Output OffValue Tag = 80,001
Output State in Continuous Rate
Scaler Tag = 1
Output OnValue = 20,000
Output OffValue = 80,001
4 MHz Count
= 20,000
4 MHz Count
= 40,000
Outputs in Period Rate and Continuous Rate with Scaler = 2
50 Hz at Z-Input
50% Duty Cycle
Scaler Tag = 2
What the Counter
Sees Internally With
Scaler Tag = 2
Counter Idle
Counter Times
Width of Pulse
4 MHz = 80,000
Output State in Period Rate
4 MHz Count = 80,000
Output State in Continuous Rate
4 MHz Count
= 20,000
4 MHz Count
= 80,000
12633-I
Scaler Tag = 2
Output OnValue Tag = 20,000
Output OffValue Tag = 80,001
Scaler Tag = 2
Output OnValue = 20,000
Output OffValue = 80,001