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The status indicators here show the status of the detector and the feedback controller, and show the reason for stopping if feedback is not running. When feedback is running all indicators in the left hand column will be green, otherwise one with be red to indicate a reason for stopping. Similarly the right hand column shows the current active state of each part of the Tune PLL system.
| Name | Stop PV | Status PV | Description |
|---|---|---|---|
| Stopped by user | :PLL:CTRL:STOP:STOP | The controller has been deliberately stopped by triggering one of the stop PVs. | |
| Detector overflow | :PLL:CTRL:STOP:DET_OVF | :PLL:STA:DET_OVF | The detector readout has overflowed. To avoid this condition reduce the readout gain :PLL:DET:SCALING_S as appropriate. |
| Magnitude error | :PLL:CTRL:STOP:MAG_ERROR | :PLL:STA:MAG_ERROR | The signal magnitude as measured by the detector is smaller than the threshold set in :PLL:CTRL:MIN_MAG_S. Avoid this by either increasing the detector readout gain or adjusting the threshold. |
| Offset overflow | :PLL:CTRL:STOP:OFFSET_OVF | :PLL:STA:OFFSET_OVF | The frequency offset has moved beyond the threshold set in :PLL:CTRL:MAX_OFFSET_S. |
Config
The Tune PLL controller is a simple PI controller. The configuration for the controller is set here.
| Name | PV | Description |
|---|---|---|
| Integral | :PLL:CTRL:KI_S | This is the integral term for the PI controller. |
| Proportional | :PLL:CTRL:KP_S | This is the proportional term for the PI controller. |
| Mag. limit | :PLL:CTRL:MIN_MAG_S | This sets a minimum value for the detector magnitude. The controller will stop if the value is too low. This should be set above 0.00005 to ensure adequate phase resolution. |
| Offset limit | :PLL:CTRL:MAX_OFFSET_S | This limits the maximum frequency offset excursion before the controller will stop. |
| Target Phase | :PLL:CTRL:TARGET_S | When the tune PLL controller is running it will work to maintain the readback phase :PLL:FILT:PHASE equal to this value. |
Control
This group contains the top level running status PV and four controls for starting and stopping the tune PLL controller.
| Name | PV | Description |
|---|---|---|
| Status | :PLL:CTRL:STATUS | Reports "Stopped" or "Running" depending whether the controller is running. |
| Start | :PLL:CTRL:START_S | Starts the controller if it is stopped. |
| Stop | :PLL:CTRL:STOP_S | Stops the controller if it is started. |
The remaining two controls are slightly anomalous, as the are shared between both axes, and thus are only present in TMBF mode, and the PV names do not include the $(axis) component; thus the full names are written below.
| Name | PV | Description |
|---|---|---|
| Start All | $(device):PLL:CTRL:START_S | Starts controllers on both axes simultaneously. If both controllers are configured with the same dwell time and are started together then they will remain synchronous. |
| Stop All | $(device):PLL:CTRL:STOP_S | Stops controllers on both axes simultaneously. |