The DVC6200 locator has been debugged successfully. When a valve position signal is sent, the downward movement functions properly. During upward movement, for example, if a valve position of 25 is set, the position first reaches around 30 before returning to 25; this happens at each point during upward movement – the position increases slightly before returning to the set value

I adjusted it 3 times, but it’s still the same – double-acting

There is a bit of overshoot; the parameters can be adjusted. If it’s not important, this works just fine as well

Try manually adjusting the PID parameters of the locator

Are you referring to the expert parameter adjustment option?

Not in operation; a single-point valve position setting is used, and the up and down movement works very well. It doesn’t function properly when it’s online

This post was last edited by white-cg on 2019-8-29 at 13:59. There are many reasons for the overshoot issue; the downward movement functions normally. During upward movement, if a valve position of 25 is set, the value first rises to over 30 before returning to 25. This happens at every point during upward movement. For now, the simplest and most direct solution is to reduce the cross-sectional area of the pneumatic pipeline leading to the lower cylinder (from the actuator to the cylinder), for example by squeezing it with pliers to flatten it a bit, etc. It is best to use the locator settings to make adjustments.

The FISHER valve configuration menu includes an option for performance optimization tuning; increasing the coefficient should reduce or eliminate overshoot.

This phenomenon is the result of overshoot. By drawing a simple block diagram of the valve positioner and the valve’s operating principle, it can be seen that it is essentially a single-loop control system. Differences in the upward and downward responses are usually caused by the force exerted on the valve core by the medium under specific operating conditions, which results in different speeds of the valve moving upward and downward, or by differences in air resistance in the two air circuits (in the case of double-acting valves). (When the upward and downward responses are the same, overshoot leads to valve oscillation.) If the locator has settings such as damping, proportionality, and gain, these settings can be adjusted to eliminate overshoot. When there is a significant difference in the upward and downward response of a double-acting valve, adjusting the actuator may not solve the problem; instead, the piping system needs to be adjusted. For example: using pipes of different diameters on both sides ； Expand the opening at the center of the pipe fitting or block part of it ； Use pliers to crush the tube… Also: leaks in the signal tubing can also cause the phenomenon you mentioned.

Configure > Guided Setup > Performance Tuner or Configure > Guided Setup > Stabilize/Optimize