Owner's manual

Rockwell Automation Publication 1756-UM536A-EN-P - April 2012 15
Module Operation Chapter 2
Counter Control Functions
The counter module provides four counter control functions:
• Up/Down Count
• Count Enable
• Reset Count
• Preset Count
The module provides two methods to invoke counter control functions:
• Hardware inputs—You can tie counter control functions to standard
hardware inputs 0…7 to let the state of external input devices directly
control the functionality of a designated counter. To configure this
method, you use the Input Configuration tab within the module’s
properties to set up ties as shown in Figure 3 on page 16
.
• Output tags—The output tag method enables you to programmatically
control the counter functions via the module’s output tags. This method
offers the most flexibility in invoking counter control functions. However,
the response time is limited due to the time required for the controller to
process your application routine.
Keep in mind the following when tying hardware inputs to counter control
functions:
• A single input can control functionality for multiple counters. For
example, you can tie input 3 to the Up/Down Count function for all eight
counters.
• Only one type of counter control function can be tied to a single input. For
example, you cannot tie both the Count Enable and Reset Count
functions to the same input.
• If you do not require hardware inputs 0…7 to support counter control
functionality, you can use the inputs as general purpose On/Off inputs
without timestamping.