my Roland RD-700NX will generate at most one message every 8ms (125 messages/second) from the continuous pedal input.

Thanks for the helpful information!

how often should I send MIDI messages

Keep in mind that it's the MIDI controller to which the pedal is connected that generates the messages and determines how many messages to generate per time (or maybe per some amount of change in the analog signal from the pedal input circuit). I'm not sure how much variability there is across the industry, but I recently discovered that my Roland RD-700NX will generate at most one message every 8ms (125 messages/second) from the continuous pedal input.

A question for Modartt.
I want to convert a regular, cheap pedal that can only create an on and off event into a pedal that responds to intermediate positions. The way the right pedal from the VPC1 does, for example. Maybe I'll use a variable resistor or an optical sensor or a magnetic one for this. It doesn't matter. But I would like to know how often should I send MIDI messages to Pianoteq? How will this be interpreted more correctly in Pianoteq? For example, 10 times per second.. 100... how often is Pianoteq ready to process messages from the pedal?
Thanks!

The more messages, the better, as Pianoteq tries to estimate the pedal velocity from the position sent by each message. I think 10 messages / sec would be too low. 100 is perfect.