Hardware reference guide

Intelligent/Special Purpose
35013379 11/2011 353
COUNTER ENABLE
Both hardware and software enables are required for an input counter to operate.
An input counter will be automatically software enabled whenever a new maximum
value is loaded or a preset (hardware or software) is sent to it.
RATE SAMPLE VALUE
The rate sample value is held and may be accessed during count operations. The
value read is from the last configured and completed rate sample interval.
QUADRATURE MODE
When the module is configured for quadrature mode operation, the counter requires
encoder pulses on inputs A and B.
In quadrature mode, all input signal edges are counted. A 60 count/revolution
encoder will produce a count of 240 for one shaft rotation.
Miscellaneous Information
Field wire to Counter 2 inputs and outputs, when configured for one 32 bit counter
with output assertion. The unused Counter 1 must have its + (plus) inputs connected
to VREF+.
Input counts and parameters are not maintained in the module at power down. The
rewrite of parameters at power up must be done with either user logic or Modzoom-
type preset panel selections.
The 200 Hz filter for each counter can be activated by strapping the Lo Filter Sel
terminal to the Return terminal. This function provides noise immunity for low
frequency applications and can also be used for relay debounce.
Operation
The following information describes the operation of various module functions.
Rate Sample
To rate sample, the module must be:
z Configured for pulse or quadrature mode.
z Configured for Rate Sample mode.
z Loaded with the Rate Sample time value.
z Enabled to count, using hardwired input and software control bits.