proportional valve

[moy945]

Good Morning, 

i'm having trouble controlling a proportional valve  i'm trying to use the accelerate function block but i'm not sure how to use it. 

i'm trying to make it rise from 0-20% after some seconds rise it to 80% and from that lower it to 80-0%

basically it's a ramp up-ramp down

could someone help??

 

or is their another method of how to control it??

[Joe Tauser]

I'd use a couple of Linear blocks controlled by a register you increment containing total seconds.  

What is your ramp rate in % per sec?  Or, better yet, could you draw a picture?

Joe T.

[Ausman]

Also, does the valve do a fixed rate of change?

cheers,

Aus

[moy945]

ok i managed to do it but starts by itself the ramp up -ramp down i'm putting some conditions so that i could control it until i press start but none of the conditions work .

 

is there a specific way of controlling it??

thanks.

[Joe Tauser]

We need to see how the linear blocks are configured.  Can you post your code?

Joe T.

[moy945]

OK the first part is the ramp down

this part is the ramp up 

[Joe Tauser]

I'm always happy to help someone who's been trying and takes the time to show or post their work.

Your blocks look like they're backwards and you don't have the proper control register.  Remember that a Linear block makes a straight line that progresses from Y1 to Y2 as the input moves from X1 to X2.

Here's what I'm guessing you want, based on an analog output ranging from 0-4095 counts, some of the numbers in your blocks, and what you asked for in your first post:

20% = 819 counts

80% = 3276 counts

Analog output to valve in MI 5

1. Ramp 1: 0% -> 20% over seconds preset stored in ML 0

2. Wait for a while - stored in ML 1

3. Ramp 2: 20% -> 80% over seconds stored in ML 2

4. Ramp 3: 80% -> 0% over seconds stored in ML 3

I made a state machine that steps through this sequence.   The pointer is in MI 0.

Take a look at the attached program.  This was written in 9.8.64

Joe T.

Ramp valve example.vlp

[moy945]

ok i understand now, I had a few errors in my code i have fixed them and i'm going to try it out.hope it works.

thanks.