Rockwell Automation 1756-XXXX ControlLogix Digital I/O Modules - Manual (Page 79)

Rockwell Automation Publication 1756-UM058G-EN-P - November 2012 79
Diagnostic Module Features Chapter 4
Diagnostic Change of State for Output Modules
If the Diagnostic Change of State feature is enabled, a diagnostic output module
sends new data to the owner-controller when one of the events described in the
table occurs.
Unlike diagnostic input modules, this feature cannot be disabled for diagnostic
output modules. There is no Enable Change of State for Diagnostic Transitions
checkbox on the Configuration tab to check or clear for diagnostic output
modules.
Fault and Status Reporting
between Input Modules and
Controllers ControlLogix diagnostic digital input modules multicast fault and status data to
any owner-controller or listening controller. All diagnostic input modules
maintain a module-fault word, the highest level of fault reporting. Some modules
use additional words to indicate fault conditions.
The following table lists the fault words and the associated tags that can be
examined in program logic to indicate when a fault has occurred for a diagnostic
input module.
All words are 32-bit, although only the number of bits appropriate for each
module’s density are used. For example, the 1756-IA16I module has a module-
fault word of 32 bits. But, because this is a 16-point module, only the first 16 bits
(0…15) are used in the module-fault word.
Table 11 - Diagnostic Change of State Events
Event Description
Receipt of output data Output module sends data when it echoes back to the owner-controller.
Diagnostic change of state Output module sends data when any change in the diagnostics output point
occurs.
Table 12 - Fault Words on Diagnostic Input Modules
Word Tag Name Description
Module-fault Fault Provides fault summary reporting. Available on all digital input
modules.
Field Power Loss FieldPwrLoss Indicates loss of field power to a group on the module. Available on
the 1756-IA8D only.
For more information, see
Field Power Loss Detection on page 74 .
Open Wire OpenWire Indicates the loss of a wire from a point on the module. For more
information, see
Open Wire Detection on page 73 .