Timed Breathing Pattern

The Resmed S9 VPAP ST has settings for TI Max, TI Min, and RR.
If I want a timed breathing pattern, controlled only by settings on the machine, to deliver approximately a TI duration of 1.4 sec and a TE duration of 2.1 sec, consider the following:
Set TI Max = 1.4 sec. Set RR = 17 BPM.
TI duration + TE duration = 1.4 + 2.1 = 3.5 sec (time for one complete breath)
60 sec / 3.5 = 17.1 BPM (pretty close to 17).
If I set TI Max to 1.4 sec, RR to 17 BPM, and Ti Min = TI max, I should, I think, get close enough to the timed breathing pattern I specified.
Would someone who knows more about S9 VPAP ST than I do please tell if my reasoning is correct? Or is there a completely different approach that is easier and/or cheaper?

theoldman22 wrote:The Resmed S9 VPAP ST has settings for TI Max, TI Min, and RR.
If I want a timed breathing pattern, controlled only by settings on the machine, to deliver approximately a TI duration of 1.4 sec and a TE duration of 2.1 sec, consider the following:
Set TI Max = 1.4 sec. Set RR = 17 BPM.
TI duration + TE duration = 1.4 + 2.1 = 3.5 sec (time for one complete breath)
60 sec / 3.5 = 17.1 BPM (pretty close to 17).
If I set TI Max to 1.4 sec, RR to 17 BPM, and Ti Min = TI max, I should, I think, get close enough to the timed breathing pattern I specified.
Would someone who knows more about S9 VPAP ST than I do please tell if my reasoning is correct? Or is there a completely different approach that is easier and/or cheaper?

I've no experience with the RR on the ST, so all I can offer is what the clinician manual says, on page 6:

for a bpm of 15, Ttot=4, i:e=1.3, TiMin=1.0, TiMax=2.0 secure exhalation time=1.3
for a bpm of 20, Ttot=3, i:e=1.0, TiMin=0.8, TiMax=1.5 secure exhalation time=1.0

in ST mode the rr is the back up rate, in case the patient doesn't initiate a breath in time.