Thomas Ales [M S E]
56 lines
2.3 KiB
Markdown
56 lines
2.3 KiB
Markdown
# Session summary — scan timeout & geometry fixes
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## Bug fixed: oscilloscope timeout on first row
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**File:** `hardware/tektronix_base.py` — `transfer_fastframe()` (~line 1414)
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The scope was configured for N frames but only triggered on fewer (e.g. 57 of 58) because
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the stage decelerates before the last laser pulse. `transfer_fastframe` looped using
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`get_fastframe_count()` (the configured maximum), so the final `read_raw()` call blocked
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waiting for data that never came and timed out.
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**Fix:** replaced `get_fastframe_count()` with a live query:
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```python
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acquired = int(self.query("ACQuire:NUMFRAMESACQuired?"))
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```
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The loop now reads exactly as many frames as the scope actually captured.
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---
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## Scan geometry overhaul
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**File:** `sc3_aui_app.py`
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### Constants added (near line 71)
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```python
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LASER_FREQ_HZ = 2000.0 # fixed laser pulse frequency
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SCAN_RAMP_MM = v² / (2a) # ≈ 3.33 mm (100² / 2×1500)
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```
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`SCAN_RAMP_MM` is the distance the stage needs to accelerate from rest to full scan
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velocity, or decelerate back to rest.
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### `_run_scan()` changes
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- `points_per_row` now uses `LASER_FREQ_HZ` instead of the param-supplied `laser_freq`.
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- Pre-scan X position is `x_start - SCAN_RAMP_MM` so the stage arrives at `x_start`
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already at full velocity (TRIGOUT_MAXV fires at the right place).
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- Scan move ends at `x_start + x_delta + SCAN_RAMP_MM` so the stage doesn't begin
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decelerating until after the last data point.
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### Travel-limit guards added (before any hardware interaction)
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Raises `ValueError` with an actionable message if the extended move would exceed the
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stage limits baked into the driver (`bbd20x.py`: X 0–110 mm, Y 0–75 mm):
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- `x_start - SCAN_RAMP_MM < 0`
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- `x_start + x_delta + SCAN_RAMP_MM > 110`
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- any Y row position outside 0–75 mm
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Error messages tell the user exactly how many mm to adjust.
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---
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## What to check / next steps
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- Verify `ACQuire:NUMFRAMESACQuired?` is the correct query string for the specific scope
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model in use (MDO/MSO series assumed; confirm against programmer manual).
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- `LASER_FREQ_HZ = 2000.0` is a temporary constant — wire it to the UI param when ready.
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- Confirm `SCAN_RAMP_MM` matches observed stage behaviour; if the BBD202 velocity profile
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is not perfectly triangular the empirical ramp may differ slightly from v²/2a.
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