You can send message to all the NCP connections using the Broadcast message to all connections on selected servers option in Actions drop-down.
In UMC, click File Access Protocols > NCP.
Click the Search icon and specify the server name.
or
Click Browse, select Server Type to list their associated servers. Select the required servers from the list, and then click APPLY.
Click NCP > Connections.
Click the Actions drop-down and select Broadcast message to all connections on selected servers.
Specify the message and click Send.
The Character limit of broadcast message is 256.
This delivers the specified broadcast message to all the NCP connections for the selected servers.