Sending RRD data via devmon to existing columns

Is it possible to send a status line to Hobbit from an external source like devmon, with the proper DS field and a value for something like percent of used memory, and have it create the rrd files and graphs?

I've tried using one of the existing rrd files as an example, sending various status lines using devmon, with no other text in the message, such as:
realmempct : 50
or
real : 50
or
memory.real : 50

But none of them appear to work.