With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
moduleSerialNumber
module Serial Number
1.3.6.1.4.1.9.5.1.3.1.1.3
format. If the module uses an alphanumeric serial number, this MIB object will return 0. This object is deprecated and replaced by entPhysicalSerialNum in ENTITY-MIB.
Back to CISCO-STACK-MIB MIB page.
IPHost Network monitor allows you to monitor moduleSerialNumber 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.