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This screen provides access to all controls for configuring a single channel of DAC output. The following PVs can be set here (all All PVs on this screen are prefixed with $(device):$(axis)):. Three groups of PVs are shown. First the graph at the top.
| Name | PV | Description |
|---|---|---|
| DAC Compensation Pre-Eemphasis Filter | :DAC:FILTER_S | This filter is applied to the generated bunch stream immediately before transmission to the DAC and can be used as a pre-emphasis filter to correct for amplifier artefacts. The valid range of taps is +-1, and the response of the filter should be adjusted to avoid overflow: this will be indicated by the DAC FIR overflow PV :DAC:FIR_OVF. |
On the left PVs controlling and monitoring the output stream:
| Name | PV | |
|---|---|---|
| FIR early clipping | :DAC:BUN_OVF | |
| Output overflow | :DAC:MUX_OVF | |
| Preemph overflow | :DAC:FIR_OVF | |
| Output delay | :DAC:DELAY_S | This is used to delay the DAC output so that the closed loop delay is a single machine revolution. |
| Output enable | :DAC:ENABLE_S | |
| DRAM input | :DAC:DRAM_SOURCE_S | Enables output to the DAC. When the MBF control IOC is restarted this is automatically set to "Off".
On the right the DRAM and MMS sources are controlled.
| Name | PV | Description | |
|---|---|---|---|
| MMS input | :DAC:MMS_SOURCE_S | Min/Max/Sum data can be sourced from before or after the pre-emphasis filter . | DRAMor from the feedback FIR stream. This last option is sourced after bunch by bunch gain adjustment but before output enable for this stream. |
| Link to Min/Max/Sum screen for DAC. | |||
| Memory input | :DAC:DRAM_SOURCE_S | Data capture to memory can be sourced from before or after the pre-emphasis filter. |
The three event indicators are as follows:
| Name | PV | Description | |||||
|---|---|---|---|---|---|---|---|
| DAC bunch FIR overflow | :DAC:BUNMMS_OVF | Shows This shows an alarm state if the current bunch-by-bunch FIR gain results in overflow for a bunch selected for output. | DAC output overflowfeedback FIR stream, as selectable as one of the MMS inputs, sees an overflow. This alarm will be shown even if this stream is being ignored. | ||||
| Event | :DAC: | MUXEVENT_LIMIT_ | OVFShows an alarm state if the combination of DAC outputs selected by the active bank control results in overflow. | DAC FIR overflow | :DAC:FIR_OVF | Shows an alarm state if overflow occurs in the pre-emphasis filterS | This should be set to a number in the range 0..1 to select the bunch motion threshold used to generate the ADC min/max event. This is generated whenever bunch motion exceeds the programmed limit and can be used to generate a trigger event. |
| DAC min/max event | :DAC:EVENT | Indicates that a bunch min/max event as configured by :EVENT_LIMIT_S has been seen. Note that this event is created as part of the Min/Max/Sum processing, so the MMS input :MMS_SOURCE_S will affect which events are seen. |