ramp with mitsubishi FX 2N

Dear all, I need HELP.

I have some problem with this PLC.
I need to create the ramp for increase / decrease the speed of one motor. The operator put into the sistem, with the touch screen, the value of speed and the distance. The program fo this machine is composed by 20 steps.

In this file you can see an example:



The supplier say me that is not possiblecreate a ramps with this plc. It's true ? O it's enought make a dedicate program in the PLC.

Unfortunatle I'm not an electrotecnical.

Wait your answer.

Thank you so much.

Any PLC that can do basic math can do a ramp. The basic formula for a ramp is

Starting_point + ((Ending_Point - Starting_Point)/(elapsed_time/ramp_time))

The formula is an algebraic variation of the basic line/slope equation y=mx+b, where
b = starting point
m = span/ramp_time, ((ending_point - starting_point)/ramp_time)
x = elapsed_time

If the PLC supports only integer math then pay attention to the order of operations, you may have re-arrange so that the division is the last operation.

correction: Starting_point + ((Ending_Point - Starting_Point)*elapsed_time/ramp_time)

thank you su much for your answer.

The system is composed by:

PLC Mitsubishi FX 2N - 64 MR
touch screen GOT 1000 Mitsubischi

Card DELTA ASDA - B

INVERTER DELTA S1

ServoMotor DELTA ECMA - C30807J5

The motor is connect with the screw, and with the screw rotation move one trolley.


Thank you.

Calimerini

Alaric said:

correction: Starting_point + ((Ending_Point - Starting_Point)*elapsed_time/ramp_time)

Click to expand...

Thanks for the answer, I have understood what you say.
But in the system I only insert the value of the speed and the space not the time

The FX2N has a "ramp" instruction see attached pdf

The time it takes to ramp between two velocities is
t01=2*x01/(v1+v0)
where:
t01 is the time between velocity0 and velocity1
x01 is the distance between where velocity0 and velocity1
v1 is the final velocity
v0 is the initial velocity
Tha ramp.pdf talked about ramping as a funciton of steps. If there is a way of equating the steps with time then you have it.

Otherwise you need to do this
f=(t-t0)/t01
v=v0*(1-f)+v1*f
t0 is the time when the velocity is at v0 at the start of the ramp. I use a free running clock for this. I have no idea what the FX2n has for a a clock.

if the FX2n has a block like the AB SCP block then one can
use the time to scale to velocity.

Now do want s curves?
f=(t-t0)/t01
f=(3-2*f)*f^2 // convert liner to 3rd order ramp
v(t)=v0*(1-f)+v1*f

Thank you so much for the answer Peter and BTalbot.

The greatest problem will be make to understand to the Chinese supplier that the ramps can be created. I don't speak Chinese, in this moment I'm in cina for follow some process.