The question is somewhat difficult to answer in general. If you have the option of sending 0% and 100% to the dimmer, then it can also be used as an on/off switch. Specifically: With my Mediola gateway, I can also use this dimmer as a pure on/off switch.
But what probably won't work: Set something on the dimmer so that dimming commands (e.g. from a radio remote control) are ignored.