Motion Event Instructions 
 
246  Rockwell Automation Publication MOTION-RM002H-EN-P-February 2018 
Execution 
Ladder Diagram 
Condition/State  Action Taken 
Prescan  The .EN, .DN, .ER, and .IP bits are cleared to false. 
Rung-condition-in is false  The .EN bit is cleared to false if either the .DN or .ER bit is true. 
Rung-condition-in is true    The .EN bit is set to true and the instruction executes. 
Postscan  N/A 
Structured Text 
Condition/State  Action Taken 
Prescan  See Prescan in the Ladder Diagram table.   
Normal execution  See Rung-condition-in is false, followed by rung is true in the Ladder Diagram table. 
Postscan  See Postscan in the Ladder Diagram table.   
Error Codes 
See Motion Error Codes (.ERR) for Motion Instructions. 
Extended Error Codes 
Extended Error Codes provide additional instruction specific information for the 
Error Codes that are generic to many instructions. See Motion Error Codes (.ERR) 
for Motion Instructions. 
Status Bits   
MDW Changes to Status Bits 
Bit Name  State  Meaning 
WatchEventArmedStatus  FALSE  The axis is not looking for a watch position event. 
WatchEventStatus  FALSE  The previous watch event is cleared. 
Examples 
When the input conditions are true, the controller disarms watch-position 
event-checking for axis1.