I need to control the DBMax / D22 via RS 485. Is it possible to control the DBMax / D22 without a PCMCIA card at all (for example using only the 65 presets set on ROM)?
Yes, it is possible to control the DBMax / D22 by RS485 without a PCMCIA card.
But, you can NOT select the ROM presets by RS485. You MUST make some user RAM presets. The RS485 preset change command are directed to the RAM bank only.