With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
tn3270sIpPuIndex
tn3270s Ip Pu Index
1.3.6.1.4.1.9.9.54.1.4.1.1.3
The PU index associated with NAU and PU objects
Back to CISCO-TN3270SERVER-MIB MIB page.
IPHost Network monitor allows you to monitor tn3270sIpPuIndex on Cisco device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Cisco multiplexers right now.