Concern 1: Local site personnel should be able to control when the system is remotely accessible.
Solution: You can tie a key or toggle switch to Digital Input 1 of the SiteManager which only allows remote access with the DI in the OFF state. In this manner, local personnel could disable/enable remote access with the turn off a key/flip of a switch at the local control panel.
Concern 2: When remote access is enabled, can more than one remote technician potentially access the same PLC, controller, etc. at the same time, possibly causing a conflict?
Solution: The SiteManager allows the user to create Agents whose primary function is to "whitelist" the only devices behind the SiteManager that can be reached remotely; however, Agents also offer additional functionality in regards to this particular topic. Here is a list of agents configured on a SiteManager:
Below we look at the custom parameters for the agent I've named "CompactLogix". Here I have added a Custom Setting of "-X". The "-X" indicates this device should have Exclusive Access: Allow only one LinkManager at a time to access this device; if a second LinkManager tries to connect, the connection will be rejected.