With IPHost Network Monitor you can run simple snmp requests against a HP device in your network.
nmSNMPListLength
nm SNMP List Length
1.3.6.1.4.1.11.2.17.4.4.1.2.1
The length of netmon's SNMP polling list, indicating the number of managed nodes actively being polled.
Back to hpov-netmon MIB page.
IPHost Network monitor allows you to monitor nmSNMPListLength on Hewlett Packard device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Cisco wireless switches right now.