102 lines
3.5 KiB
Markdown
102 lines
3.5 KiB
Markdown
# Coherent Sapphire Laser Communication Protocol Specification
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This document defines the serial communication protocol used by Coherent Sapphire lasers, as implemented in the Sapphire ESP32 Controller.
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## 1. Physical Layer
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- **Interface**: RS-232 (Requires TTL conversion for ESP32/Arduino)
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- **Baud Rate**: 19200 bps
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- **Data Bits**: 8
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- **Parity**: None
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- **Stop Bits**: 1
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- **Flow Control**: None
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## 2. Message Format
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### 2.1 Commands
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Commands are sent as ASCII strings terminated by a carriage return (`\r`) or a newline (`\n`).
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- **Queries**: Start with `?` (e.g., `?P`)
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- **Settings**: Use `=` to assign values (e.g., `P=100.0`)
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### 2.2 Responses
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Responses are returned as ASCII strings, typically terminated by `\r\n`.
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- Some configurations may include a prompt character (`>`) at the start or end of a response.
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- Responses may include a prefix such as `Sapphire -> ` depending on the device firmware version and settings.
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---
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## 3. Query Commands (Telemetry)
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| Command | Description | Unit | Data Type |
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| :--- | :--- | :--- | :--- |
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| `?P` | Actual Output Power | mW | Float |
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| `?C` | Laser Diode Current | A | Float |
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| `?BT` | Baseplate Temperature | °C | Float |
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| `?DT` | Laser Diode Temperature | °C | Float |
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| `?PST` | Power Supply/Controller Temperature | °C | Float |
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| `?DST` | Setpoint Temperature | °C | Float |
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| `?STA` | System Status Code | - | Integer (See Sec 5) |
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| `?FF` | Fault Flags | - | Bitmask (See Sec 6) |
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| `?HH` | Laser Head Operating Hours | Hours | Integer |
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| `?PSH` | Controller Operating Hours | Hours | Integer |
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| `?WAVE` | Laser Wavelength | nm | Float |
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| `?MINLP` | Minimum Rated Laser Power | mW | Float |
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| `?MAXLP` | Maximum Rated Laser Power | mW | Float |
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| `?DRC` | Diode Reserve Current | A | Float |
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---
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## 4. Control Commands
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### 4.1 Power Control
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- **Command**: `P=VALUE`
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- **Example**: `P=50.5` sets the laser output to 50.5 mW.
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- **Response**: Typically `OK` or the new value.
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### 4.2 Configuration
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- **Echo Control (`E`)**:
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- `E=0`: Disable command echo (recommended for automated controllers).
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- `E=1`: Enable command echo.
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- **Prompt Control (`>`)**:
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- `>0`: Disable the `>` prompt character in responses.
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- `>1`: Enable the `>` prompt character.
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---
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## 5. Status Codes (`?STA`)
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The `?STA` command returns an integer representing the current state of the laser:
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| Code | State | Description |
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| :--- | :--- | :--- |
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| `1` | Start Up | Initializing electronics |
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| `2` | Warmup | Bringing temperatures to setpoint |
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| `3` | Standby | Ready to turn on |
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| `4` | Laser On | Diode is active and emitting |
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| `5` | Laser Ready | Stabilized and ready for use |
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| `6` | Error | System fault detected |
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---
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## 6. Fault Flags (`?FF`)
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The `?FF` command returns a bitmask representing internal diagnostics. Key bits identified:
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- **Bit 8 (Value 256)**: **Warming**. Set during the thermal stabilization phase.
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- **Bit 13 (Value 8192)**: **Ready/OK**. Indicates normal operation.
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- **Other Values**: Any value other than `0` or `8192` usually indicates a fault condition.
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---
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## 7. Implementation Notes
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### 7.1 Polling Rates
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Coherent recommends a maximum polling rate of **1 Hz** (1000ms) for telemetry queries to ensure stability of the internal controller.
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### 7.2 Connection Sequence
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1. Send `?FF` to verify communication and check for initial faults.
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2. Disable echo (`E=0`) and prompt (`>0`) for cleaner machine-to-machine parsing.
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3. Query static parameters (`?WAVE`, `?MAXLP`, `?HH`) once at startup.
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4. Enter a cyclic loop for dynamic telemetry (`?P`, `?C`, `?BT`, `?STA`).
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