Check this link ..hope it will help you..
VMware KB: Configuring Serial Port Communication over Network between two virtual machines
Yours, Phillips
Dear sir
It seems to use SOL between two virtual machines on ESXi Server.
Is there any way to connect to ESXi Server/Host itself by SOL(from remote client server) and monitor the Host Server screen?
If you just want to monitor the host logging and any activity, then yes. You can confirm the SOL configured in the esxcfg-advcfg -s COM1 /Misc/LogPort
Check this kb for serial monitoring for booting, activity monitoring and debugging also
VMware KB: Enabling serial-line logging for an ESXi/ESXi host