MAX voltage scaling problem

[olivier66]

Hi,
I have an issue using max when I try to build a scale for my measurement,
I have a voltage acquisition + 5v to - 5v and my scale must be -5v = 0 RPM, 5v = 7500 RPM I tried to build a scale for this using linear scale so the transfert function is Y(RPM) = 1500X(v), I also tried to use a map range scale withe the values above but I get an error when  I save the task "error -200077 occured a DAQ Assistant Possible Reasons: property AI.Min
requested -5; value begin with 0 ; values end with 7500"

Even if I don't get any error on the linear scale The larger value I can get is 322.9474 RPM I cannot go further and curiously when I am not using any scale the voltage value can go over 1(V)  which according to the scale calcul will give 1500 RPM

I don't understand why RPM value using scale from V to RPM is stuck under 322.9474 RPM, maybe I did not build my scale correctly...

Thanks for answers

Olivier

[RobertoBozzolo]

Since you have a total measure of 7500 rpm over 10 V with an offset of half scale, it seems to me that you should define your custom scale as y=750X + 3750.

So you have to:

1. Set in MAX channel voltage range to -5 ÷ 5
2. Define the custom scale on the channel setting units to rpm
3. Come back to channel definition and put limits (rpm) to 0 ÷ 7500