The reason to power up the expansion modules before the control unit is that the control unit needs to discover the expansion units during the startup process. If the expansion units are not powered on first, the control unit may fail to detect and configure them properly.
Contribute your Thoughts:
Chosen Answer:
This is a voting comment (?). You can switch to a simple comment. It is better to Upvote an existing comment if you don't have anything to add.
Submit