Emerson Exchange 365

A total download of the controller does not trigger switchover.  A partial download also does not trigger a swtichover...it simply downloads and re-inititalizes the component that is downloaded.

From books on line (www3.emersonprocess.com/.../download_data.htm) :

Full (Total) Download (Workstation or Controller)

To download the entire configuration of a workstation or controller, select the item you want to download, right-click, and then click the Download option from the menu. This downloads the entire configuration for the node selected (workstation or controller) and is called a full (total) download.

Use a full download when the node has not yet been downloaded or has no configuration. Total controller downloads should be avoided when the process is running. If there is already configuration present in the controller, a total download will generally cause parameter values in the controller to be replaced with those from the configuration database. There are some exceptions where matching behavior occurs, such as in controller function blocks directly connected to output channels and for fieldbus shadow blocks. Depending on your configuration you could experience an output disruption on a total controller download.

Also, take a look at the article on controller redundancy (www3.emersonprocess.com/.../controllerredundancy.htm)

Switchovers

A switchover from the active to the standby controller can occur for the following reasons:

• Hardware failure within the active controller
• Communications failure between the active controller and the I/O subsystem
• Communications failure of both the primary and secondary network connections in the active controller
• Removal of the active controller from the carrier
• Manual switchover request
• Loss of power supply for the active controller
• Memory failure (the active controller detects a RAM or ROM failure)
• Software watchdog timer trip