I am using an MX-800 and was of the understanding that I could take the output from my MRF-200 (that was formerly used for an Ir emitter) and plug it into the 990 Ir input. I expected that I might have to cut the output a little bit by using a series resistor. This is a surprise.

Exactly what does the 990 expect (voltage, current, data format) for an input? What kind of translation does an interface module perform? Is there an interface module for the MRF-200?