Siemens Cpu226

Siemens Cpu226
In cpu 226 using EM235 extension module we are taking 0-20 mA out put

In one application when I0.0 is high current output should go out based on AIW0 (input). if at this stage input is 20mA than out put immediatele jumps from 0 to 20 that is 0 % to 100%. I want to send out put through AQW0 SLOWLY. may be 10% every 10 min.
can any body suggest a program using microwin3.2.
thanks Looking for a reply
Utpal Chatterjee

In one application when I0.0 is high, current output should go out based on AIW0 (input).

If at this stage input is 20mA than output immediately jumps from 0 to 20 that is 0 % to 100%. I want to send output through AQW0 SLOWLY. may be 10% every 10 min.


If you simply want a constant rate of increase/decrease (a low rate of increase/decrease) to a target speed, then...

Use the Analog Input numeric value to calculate the current numeric target value for your analog output. Do this calculation every scan.

Compare your current output to the target output.

If the current output is less than the target output, then you need to increase the current output (inc your speed).

If the current output is more than the target output, then you need to decrease the current output (dec your speed).

Use a timer to specify your "rate", that is, how often you inc/dec your output value.

If you are increasing and your current output is still below the target value, then ADD to the drive-value.

If you are decreasing and your current output is still above the target value, then SUB from the drive-value.

If you leave it like this, your output will dither around the target value.

If you want to bring it to a fixed value, then, when you reach the target, save the current output value as "Was Target" and stop the timer.

Then, constantly keep calculating and comparing the current Target against the "Was Target".

If the value changes, reactivate your timer.

The smaller your inc/dec number, the smoother and longer your transition will be.

Adjust to taste.

The analog system is 12 bit and hence you have a value between 0 and 32000.
You now want a 10% change every 10 minutes therefore total time is 100 minutes or 6000 seconds

A one bit change is required every 0.1875 seconds

Since the smallest timer is 1ms, make a two bit change every 375ms

Set the PT on a 1ms TON to be 375, using T32 or T96

Set up the timer to act as an on delay (See manual, use a flag bit).
I would include your I0.0 in with the flag bit to the IN.

The NC I0.0 is also used to reset an up/down counter.
Count up is enabled when the analog input is greater than the counter value.

Count down being enabled if the analog input is smaller than the counter value.

Since you need to increment by two bits duplicate the counter circuit
in the next network

Finally move the counter value to the analog output.