Rockwell Automation 1797-ACNR15 ControlNet Ex Redundant Media Adapter - Manual (Page 13)

ControlNet Ex Redundant Media Adapter 13
Publication 1797-5.14 - March 2010
FLEX Ex Output Module Operation
Refer to the following communication monitoring and power-up state
behavior.
Flexbus Communication Monitoring
The module monitors flexbus communication activity and the state of its
Output Enable bit. If it detects loss of flexbus communication activity or the
Output Enable bit transitioning to 0, it can be programmed to:
• continue writing the last valid received data to the outputs (hold last
state).
• reset the outputs.
• write the local module fault state value to the output, depending upon
the module type.
This mechanism primarily targets fault behavior for loss of backplane
communication.
Power-up State Behavior
The system and modules use the Output Enable bit at system power-up. The
power-up state of the Output Enable bit is 0 and must be transitioned to 1
through application program control to initialize activity of a module’s
outputs.
Before the Output Enable bit is transitioned to 1, module outputs remain off.
Once the initial power-up and application-program control transitions the
Output Enable bit to 1, and module output activity begins, subsequent
transitions of the Output Enable bit by any source will cause the output
module to apply the local module fault state.