Files
scanengine-3/hardware/helios_laser.py
T
Thomas Ales eff589d901 Helios: don't let an unlabelled reply pass for a register's value
_value_in()'s last resort was to accept any line it could not attribute as
the answer to whatever had just been asked.  That fallback exists for the
serial numbers, which come back bare — but it applied to every query, so a
stray "32" could be read as a diode current of 32 mA.  32 is also what a
status register reads with bit 5 set (LER "Over voltage laser diode", LCE
"Door switch open", CCE "Q-switch under/over temperature"), which is
exactly the value the panel is stuck on.

Only CSR and HSR now accept an unlabelled reply; every other read has to
see its own mnemonic in the line.  A read that cannot be attributed returns
None, and the panel shows "laser: ? mA" instead of leaving the last good
value on screen looking live — a stale reading and a setpoint that refuses
to move are indistinguishable otherwise.

tools/helios_lds_probe.py is the diagnostic for the underlying question:
it talks to the controller with no reply parsing at all and prints every
byte, so the transcript says whether LDS answers for itself, whether the
write is taken, and which flags the registers hold before and after.  The
status-register tables move to hardware/helios_registers.py so the probe
can decode them without importing the Qt app.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
2026-09-08 07:48:06 -05:00

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"""
Helios Laser System Driver
Basic implementation for controlling the Helios pulsed laser.
"""
import time
import logging
from typing import Optional, List
from enum import Enum
from hardware.serial_util import open_8n1
logger = logging.getLogger(__name__)
class PulseMode(Enum):
"""Helios pulse mode enumeration"""
SINGLE_PULSE = 0
CONTINUOUS_GATING = 1
CONTINUOUS_PULSING = 2
class HeliosLaser:
"""
Driver for Helios pulsed laser system.
Communication: RS-232, 9600 baud, 8N1
Commands are ASCII strings terminated with CR
"""
def __init__(self, port: str = None, timeout: float = 1.0):
"""Initialize Helios laser driver."""
self.port = port
self.timeout = timeout
self.serial = None
self.is_connected = False
@staticmethod
def list_available_ports() -> List[str]:
"""List available serial ports, likeliest devices first."""
from hardware.serial_util import list_port_devices
return list_port_devices()
def connect(self, port: str = None) -> bool:
"""Connect to the Helios laser."""
if port:
self.port = port
if not self.port:
logger.error("No port specified")
return False
try:
self.serial = open_8n1(self.port, baudrate=9600, timeout=self.timeout)
time.sleep(0.1) # Allow time for connection to stabilize
self.is_connected = True
logger.info(f"Connected to Helios laser on {self.port}")
return True
except Exception as e:
logger.error(f"Failed to connect to Helios laser: {e}")
self.is_connected = False
return False
def disconnect(self):
"""Disconnect from the laser"""
if self.serial and self.serial.is_open:
try:
# Disable laser before disconnecting
self.set_laser_enable(False)
self.serial.close()
logger.info("Disconnected from Helios laser")
except Exception as e:
logger.error(f"Error during disconnect: {e}")
self.is_connected = False
self.serial = None
def _send_command(self, command: str) -> bool:
"""Send a command to the laser."""
if not self.is_connected or not self.serial:
logger.error("Not connected to laser")
return False
try:
cmd_bytes = (command + '\r').encode('ascii')
self.serial.write(cmd_bytes)
logger.debug(f"Sent command: {command}")
return True
except Exception as e:
logger.error(f"Failed to send command '{command}': {e}")
return False
# A reply can run to more than one line. Every status-register query
# answers with the value and then a decode line:
#
# LCE = 2
# Bit 15..0: 0000 0000 0000 0010
#
# At 9600 baud those trailing ~30 characters are still on the wire when
# read_until() returns the first line, so reset_input_buffer() cannot
# drop them. Left there they become the next query's "answer", and
# every reply after that is one line behind — a register read reported
# as a "Bit 15..0" string, and the reads around it timing out on a
# leading blank line. So: match a reply to the command that asked for
# it, and read off the rest of it before the next command goes out.
TRAILING_QUIET_S = 0.05 # the line counts as idle after this long
MAX_REPLY_LINES = 8
def _read_line(self) -> Optional[str]:
"""One CR-terminated line without its framing; None if nothing came."""
raw = self.serial.read_until(b'\r')
if not raw:
return None
return raw.decode('ascii', errors='replace').strip()
def _read_pending_lines(self) -> List[str]:
"""Every further line the controller sends before the line goes quiet."""
lines: List[str] = []
deadline = time.monotonic() + self.TRAILING_QUIET_S
while True:
if self.serial.in_waiting:
line = self._read_line()
if line:
lines.append(line)
deadline = time.monotonic() + self.TRAILING_QUIET_S
continue
if time.monotonic() >= deadline:
return lines
time.sleep(0.005)
# The only replies that come back without naming what they answer.
# Every other line has to identify itself: an unlabelled number is not
# evidence that it is *this* register's number, and taking one on faith
# is how a status register's value ends up displayed as a diode current.
UNLABELLED_REPLIES = frozenset({"CSR", "HSR"})
@classmethod
def _value_in(cls, line: str, mnemonic: str) -> Optional[str]:
"""The value `line` holds for `mnemonic`, or None if it isn't its reply.
The controller answers "LDF = 20000 ns". A line naming a different
mnemonic is the tail of an earlier reply, and "Bit 15..0: ..." is a
status register's decode line; neither is an answer to this query.
A line naming nothing counts only for the serial numbers, which is
the one reply known to come back bare.
"""
head, sep, tail = line.partition('=')
if sep:
named = head.split()
if named and named[0].upper() != mnemonic:
return None
fields = tail.split() # drop the unit suffix ("ns", "mA", "m°C")
return fields[0] if fields else None
if line.lower().startswith("bit"):
return None
fields = line.split()
if fields and fields[0].upper() == mnemonic:
return fields[1] if len(fields) > 1 else None
if mnemonic in cls.UNLABELLED_REPLIES:
return line
return None
def _query(self, command: str) -> Optional[str]:
"""Send a query and return the value from its response.
Reads until this command's reply arrives rather than sleeping a fixed
interval: the device usually answers in a few ms, so the old
unconditional 0.05 + 0.2 s cost ~250 ms per query and made an 8-query
status poll take ~2 s — longer than the 1 s interval that scheduled
it.
"""
fields = command.split()
mnemonic = fields[0].upper() if fields else ""
try:
# Anything volunteered while the port was idle answers no command.
self.serial.reset_input_buffer()
if not self._send_command(command):
return None
deadline = time.monotonic() + self.timeout
for _ in range(self.MAX_REPLY_LINES):
line = self._read_line()
if line is None:
break # nothing arrived within the timeout
if line:
logger.debug(f"Query '{command}' line: {line!r}")
value = self._value_in(line, mnemonic)
if value is not None:
for extra in self._read_pending_lines():
logger.debug(f"Query '{command}' trailing: {extra!r}")
return value
if time.monotonic() >= deadline:
break
logger.warning(f"Query '{command}' timed out after {self.timeout}s")
self._read_pending_lines()
return None
except Exception as e:
logger.error(f"Failed to read response for '{command}': {e}")
return None
def _write_command(self, command: str) -> bool:
"""Send a command with no value to read back, and clear whatever the
controller prints in acknowledgement — left in the buffer, that is
what the next query would read as its own answer.
"""
if not self._send_command(command):
return False
try:
for line in self._read_pending_lines():
logger.debug(f"Command '{command}' reply: {line!r}")
except Exception as e:
# The command went out; only the tidy-up failed.
logger.error(f"Failed to read the reply to '{command}': {e}")
return True
# Section 6 of the operator's manual, under Syntax:
#
# Commands or set values can be discarded by the controller
# unintentionally. It is recommended to query the set value after
# the command is entered to confirm the actual value.
#
# (The command table repeats it: "Query the command to confirm it was
# accepted.") A setter that only writes therefore cannot report whether
# it worked, and the panel's next status poll reads back the old value —
# which looks exactly like the GUI refusing the operator's number.
SET_RETRIES = 3
SET_SETTLE_S = 0.05 # let the controller store it before reading
def _write_verified(self, mnemonic: str, value: int) -> bool:
"""Write `value` to `mnemonic`, and confirm the controller took it.
Returns False if the read-back never matches, leaving the controller
holding whatever value it kept — the caller is expected to say so
rather than let the discarded write pass for a successful one.
"""
for attempt in range(1, self.SET_RETRIES + 1):
if not self._write_command(f"{mnemonic} {value}"):
return False
time.sleep(self.SET_SETTLE_S)
readback = self._query_int(mnemonic)
if readback == value:
return True
logger.warning(
f"'{mnemonic} {value}' not accepted: controller reports "
f"{readback} (attempt {attempt}/{self.SET_RETRIES})")
return False
def _query_int(self, command: str) -> Optional[int]:
"""Query a value that should parse as an int; None if absent/unparseable."""
raw = self._query(command)
if raw is None:
return None
try:
return int(raw)
except ValueError:
logger.error(f"Query '{command}' returned non-integer {raw!r}")
return None
def set_frequency_hz(self, frequency: int) -> bool:
"""Set laser pulse frequency in Hz."""
if not (16700 <= frequency <= 125000):
logger.error(f"Frequency {frequency} Hz out of range (16700-125000)")
return False
# Convert frequency to period in nanoseconds
period_ns = int(1e9 / frequency)
# Clamp to valid range (8000-60000 ns)
if not (8000 <= period_ns <= 60000):
logger.error(f"Period {period_ns} ns out of range (8000-60000)")
return False
return self._write_verified("LDF", period_ns)
def set_current_ma(self, current: int) -> bool:
"""Set pump diode pulse current (LDS) in mA.
False means the controller did not take the value — see
_write_verified. The manual's range for LDS is 0-7000 mA; the
2000 mA ceiling here is this rig's limit, not the protocol's.
"""
if not (0 <= current <= 2000):
logger.error(f"Current {current} mA out of range (0-2000)")
return False
return self._write_verified("LDS", current)
def set_pulse_mode(self, mode: PulseMode) -> bool:
"""Set pulse mode.
Note from the manual's LDG entry: "LDF has to be set again after LDG
is changed, except for single pulse triggering" — so a caller that
changes the mode has to re-send the frequency.
"""
command = f"LDG {mode.value}"
return self._write_command(command)
def set_laser_enable(self, enable: bool) -> bool:
"""Enable or disable laser emission."""
command = f"LDO {1 if enable else 0}"
success = self._write_command(command)
if success:
state = "enabled" if enable else "disabled"
logger.info(f"Laser {state}")
return success
def is_laser_enabled(self) -> bool:
"""True if laser emission is currently enabled."""
return self._query_int("LDO") == 1
def get_frequency_hz(self) -> Optional[int]:
"""Current laser frequency in Hz, or None on error."""
period_ns = self._query_int("LDF")
if not period_ns:
return None
return int(1e9 / period_ns)
def get_current_ma(self) -> Optional[int]:
"""Current pump diode current in mA, or None on error."""
return self._query_int("LDS")
def _query_millicelsius(self, command: str) -> Optional[float]:
"""Query a temperature register (milli-°C) and convert to °C."""
value = self._query_int(command)
return None if value is None else value / 1000.0
def get_diode_temp_c(self) -> Optional[float]:
"""Diode temperature in °C (LTA, 5000–50000 milli-°C)."""
return self._query_millicelsius("LTA")
def get_power_stage_temp_c(self) -> Optional[float]:
"""Power stage temperature in °C (LTT, 5000–65355 milli-°C)."""
return self._query_millicelsius("LTT")
def get_qswitch_temp_c(self) -> Optional[float]:
"""Q-switch temperature in °C (EOA, 5000–50000 milli-°C)."""
return self._query_millicelsius("EOA")
def get_controller_serial(self) -> Optional[str]:
"""Controller serial number, or None on error."""
return self._query("CSR")
def get_head_serial(self) -> Optional[str]:
"""Laser head serial number, or None on error."""
return self._query("HSR")
def get_status_registers(self) -> tuple:
"""Query the LER, LCE and CCE status registers.
Each is a bitmask (sum of flags); non-zero means active faults,
cleared with reset_faults(). Returns (ler, lce, cce), any of which
is None if that register could not be read.
"""
return (self._query_int("LER"), self._query_int("LCE"),
self._query_int("CCE"))
def reset_faults(self) -> bool:
"""
Execute the controller reset sequence to clear status registers.
Protocol-specified sequence: CCE 0 -> LCE 0 -> LER 0
Returns:
True if all three commands sent successfully
"""
ok = True
ok = self._write_command("CCE 0") and ok
time.sleep(0.1)
ok = self._write_command("LCE 0") and ok
time.sleep(0.1)
ok = self._write_command("LER 0") and ok
if ok:
logger.info("Fault reset sequence sent")
return ok
def get_remote_enable(self) -> Optional[bool]:
"""Remote enable state (LRE — utility connector pin 8); None on error."""
value = self._query_int("LRE")
return None if value is None else value == 1
def send_raw_command(self, command: str) -> Optional[str]:
"""Send a raw command and return its whole unparsed reply (diagnostics).
Every line comes back, the "Bit 15..0: ..." decode line included:
seeing the entire reply is the point of the raw console.
"""
if not self.is_connected or not self.serial:
logger.error("Not connected to laser")
return None
try:
self.serial.reset_input_buffer()
if not self._send_command(command):
return None
first = self._read_line()
lines = [first] if first else []
lines += self._read_pending_lines()
return "\n".join(lines)
except Exception as e:
logger.error(f"send_raw_command error: {e}")
return None
def set_remote_enable(self, enable: bool) -> bool:
"""Set the remote enable state (LRE - utility connector pin 8)."""
command = f"LRE {1 if enable else 0}"
return self._write_command(command)
# No __del__: it used to call disconnect(), which disables the laser and
# writes to the serial port from the garbage collector at an
# unpredictable time (including interpreter shutdown, when the port may
# already be torn down). Callers close the driver explicitly.