Instruction Manual

Rockwell Automation Publication 1769-UM006E-EN-P - July 2013 111
Diagnostics and Troubleshooting Chapter 5
Module Operation versus
Counter Operation
The module performs operations at two levels:
• Module level
• Counter level
Module-level operations include functions, such as powerup, configuration, and
communication with a bus master, such as a MicroLogix 1500 controller.
Counter-level operations include counter-related functions, such as data
conversion and overflow or underflow detection.
Internal diagnostics are performed at both levels of operation. When detected,
module error conditions are immediately indicated by the module status
indicator. Both module hardware and configuration error conditions are reported
to the controller. Counter overflow or underflow conditions are reported in the
module’s input data table. Module hardware errors are typically reported in the
controller’s I/O status file. Refer to your controller manual for details.
Counter Defaults
When the module powers up, all output array and configuration array values are
set to their default values. See
page 66 in Chapter 4 or Appendix D on page 149
for default values. All input array values are cleared. None of the module data is
retained through a power cycle.
In effect, this means that power cycling clears the module with these results:
• Stored counts are lost.
• Faults and flags are cleared.
• Outputs are off.
The bus master will attempt to write program data to the output array and
configuration array.