By browsing through Siemens' web site, I have found interesting idustriall controllers that have PID built in functions. Controllers are from SIPART familly and more info can be found
here:
I have downloaded manual and found one interesting part which I printed and posted as attchment here.
For example, if this controller is used to control temperature by manipulating some electric motor valve, ideal configuration would be so called "Three-position step controller with internal feedback"
It is obvious that controller energizes one of two output relays that opens or closes valve. This is practically "step controller" (by step, I mean that output is changing in steps).
However, it is not very clear to my why this so called "internal feedback" is used. It seems that CO (to output relays) is returned to some kind of hysteresis switch with some kind of smoothing filter (maybe first order filter).
Do you have any similar experience with this kind of controllers?
Also terminology is somewhat strange to me.
Of course there is also external feedback where "In S-controllers with external feedback the ”internal position control circuit” is replaced by a
real position controller (with the K-controller output y as a setpoint and the position feedback
y R as an actual value)."
If someone is willing to read, whole manual can be found here
I mostly worked with pure software controllers (PID) usually where step output is connected to the drive via DCS module and never really thought about it.
Concepts of internal and external feedback is little bit fuzzy to me and perhaps it has its ancient roots...
Any comments are welcome
here:
I have downloaded manual and found one interesting part which I printed and posted as attchment here.
For example, if this controller is used to control temperature by manipulating some electric motor valve, ideal configuration would be so called "Three-position step controller with internal feedback"
It is obvious that controller energizes one of two output relays that opens or closes valve. This is practically "step controller" (by step, I mean that output is changing in steps).
However, it is not very clear to my why this so called "internal feedback" is used. It seems that CO (to output relays) is returned to some kind of hysteresis switch with some kind of smoothing filter (maybe first order filter).
Do you have any similar experience with this kind of controllers?
Also terminology is somewhat strange to me.
Of course there is also external feedback where "In S-controllers with external feedback the ”internal position control circuit” is replaced by a
real position controller (with the K-controller output y as a setpoint and the position feedback
y R as an actual value)."
If someone is willing to read, whole manual can be found here
I mostly worked with pure software controllers (PID) usually where step output is connected to the drive via DCS module and never really thought about it.
Concepts of internal and external feedback is little bit fuzzy to me and perhaps it has its ancient roots...
Any comments are welcome