Using Interator Instruction on COmpactLogix

[wsy_nte 0]

I used Integrator instruction on Compactlogix, how to define integrator gain? Any relation with scan time? I put the integrator instruction on peridic task with priority 7, rate 20 mS. Thank you. James

[Keith Menges 0]

As long as your timing mode is set to periodic the instruction will use the Task period to calculate the integral. So task period times won't affect the integral sum. The easiest way to evaluate what will happen with different gains is to look at what happens to a unit step input. If the integral sum starts at zero, the integrator gain is set to 1 and you make a zero to 1 step input to the instrruction the output of the instruction will be 1 after 1 second. It will be 2 after 2 seconds. Taking the same initial conditions except for setting the gain to 2, the instuction will output 2 after 1 second and 4 after 2 seconds. Notice that the gain is applied to the input prior to summing. This means the gain won't affect the limits, only rate at which the limits are reached. What are you using the instruction for? Keith