Program Structure

Features of Rockwell PLC

Rockwell PLC is designed so that the data stored in PLC at the power-off is maintained.

Therefore, once the power supply to PLC is shut-off due to blackout or other reasons, an AOI under execution keeps the status. Once the power supply recovers and the execution of AOI resumes, the AOI will start the process from the point at the power-off.

It may show unexpected behavior, depending on the robot condition.

As a countermeasure for that, set the "EnableIn" of AOI to "FALSE". It will reset the internal process of AOI.

Programming Structure

The following shows the Command-Slave function-used program structure created by "Studio 5000".

1. MC_ReadAxesGroup

To read robot-related data, such as robot motion status, from a robot controller and save it to "AxisGroup". Data obtained by this AOI will be used to control robots from other AOI. 
Therefore, when using Command-Slave function, be sure to place this AOI at the top of the program.

For details about this AOI, refer to "MC_ReadAxesGroup" of Command-Slave Reference Guide_Rockwell.

2. MC_Initialize

To obtain the Command-Slave version of the PLC and the robot controller and check if they are the same.
If the Command-Slave version of the PLC and the robot controller are different, the robot may fail to run properly. Once the communication has been established, this AOI monitors whether if the PLC and the robot controller communicate properly. 
Therefore, place this AOI prior to any AOIs other than "MC_ReadAxesGroup".

For details about this AOI, refer to "MC_Initialize" of Command-Slave Reference Guide_Rockwell.

3. MC_Power

To make AOI with the AOI category "Motion" executable and turn on the robot motor. AOI with the AOI category "Motion" needs to be made executable by this AOI before execution.
Therefore, place this AOI prior to AOI with the AOI category "Motion" .

For details about this AOI, refer to "MC_Power" of Command-Slave Reference Guide_Rockwell.

4. MC_WriteAxesGroup

To send an instruction in "AxesGroup", which has been updated by other AOI of Command-Slave, to the robot controller. The robot controller controls robots by receiving the instruction from this AOI. 
Therefore, when using Command-Slave function, be sure to place this AOI in the end of the program.

For details about this AOI, refer to "MC_WriteAxesGroup" of Command-Slave Reference Guide_Rockwell.