remove target_attr, keep target signal #535
Conversation
|
@gfabbris This is ready for your review. |
|
@gfabbris This is the most important to review (for you) on this project at this time. |
| @@ -84,7 +95,7 @@ def cb_readback(self, *args, **kwargs): | |||
| """ | |||
| Called when readback changes (EPICS CA monitor event). | |||
| """ | |||
| diff = self.readback.get() - self._target.get() | |||
| diff = self.readback.get() - self.setpoint.get() | |||
There was a problem hiding this comment.
This won't work well for some devices in which the setpoint changes when a ramp is used. For example, this is the case for the lakeshore 340. So, it should be diff = self.readback.get() - self.target.get()
There was a problem hiding this comment.
The setpoint is the ultimate temperature where the controller is headed. The _target is the interim required value for the temperature control loop. (For example, a controller's PID loop will ramp _target as the immediate objective to calculate the following error: readback - _target.) This _target value may be changed incrementally (ramped) by the controller for a controlled transition from current to setpoint. We do not need to examine the controller's interim _target to determine if the controller has reached the requested temperature.
Definitely: done = |readback - setpoint| <= tolerance
There was a problem hiding this comment.
Currently, the Lakeshore 340 EPICS supports ramps the setpoint PV. Thus I think it's not great to call it setpoint in EPICS and target in Bluesky.
There was a problem hiding this comment.
You're saying the EPICS Lakeshore support uses setpoint for the interim setpoint of the ramp?
Doesn't the Lakeshore have a PV that reports where it is headed? That's the PV to be called setpoint in Bluesky to be consistent with how it is used in other positioners, such as EpicsMotor.
The PTC10 has both: a setpoint where the controller is headed (that is setpoint in bluesky) and a setpoint for the PID loop (that would target in bluesky but this interim goal is not interesting to the user).
An interesting case is when |target - setpoint| <= tolerance, that's when we expect to be close enough that |readback- setpoint| <= tolerance could become True.
There was a problem hiding this comment.
We would use this for more controllers than the Lakeshore?
There was a problem hiding this comment.
@gfabbris Can you review again?
|
Will need to resolve merge conflicts with upstream branch due to new content in main branch. |
|
Upstream changes (from |
|
@gfabbris Ready for your review again. |
refactor (per #531)
target_attrand_targetintotarget, end user could override with named EpicsSignal if desired.