With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
tn3270sStartupTime
tn3270s Startup Time
1.3.6.1.4.1.9.9.54.1.1.1.1.5
The timestamp when the tn3270 server started.
Back to CISCO-TN3270SERVER-MIB MIB page.
IPHost Network monitor allows you to monitor tn3270sStartupTime on Cisco device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Cisco routers right now.