With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
cswStackPowerNumMembers
csw Stack Power Num Members
1.3.6.1.4.1.9.9.500.1.3.1.1.5
This object indicates the number of members in the power stack.
Back to CISCO-STACKWISE-MIB MIB page.
IPHost Network monitor allows you to monitor cswStackPowerNumMembers on Cisco device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Cisco switches right now.