Hello robmasten, With the MD3xxx units only support SNMP traps & don’t support SNMP polling.  That is why you are only able to find SNMP trap setup & not any information on polling setup.   Please let us know if you have any other questions.
I can find plenty of whitepapers for snmp trap setup, but nothing to configuring/allowing snmp polling of an MD3200i... can someone point me in the right direction.
MD3200i - SNMP Polling