klipper/klippy/gcode.py

# Parse gcode commands
#
# Copyright (C) 2016-2018  Kevin O'Connor <kevin@koconnor.net>
#
# This file may be distributed under the terms of the GNU GPLv3 license.
import os, re, logging, collections
import homing, kinematics.extruder

class error(Exception):
    pass

# Parse and handle G-Code commands
class GCodeParser:
    error = error
    RETRY_TIME = 0.100
    def __init__(self, printer, fd):
        self.printer = printer
        self.fd = fd
        # Input handling
        self.reactor = printer.get_reactor()
        self.is_processing_data = False
        self.is_fileinput = not not printer.get_start_args().get("debuginput")
        self.fd_handle = None
        if not self.is_fileinput:
            self.fd_handle = self.reactor.register_fd(self.fd, self.process_data)
        self.partial_input = ""
        self.pending_commands = []
        self.bytes_read = 0
        self.input_log = collections.deque([], 50)
        # Command handling
        self.is_printer_ready = False
        self.base_gcode_handlers = self.gcode_handlers = {}
        self.ready_gcode_handlers = {}
        self.mux_commands = {}
        self.gcode_help = {}
        for cmd in self.all_handlers:
            func = getattr(self, 'cmd_' + cmd)
            wnr = getattr(self, 'cmd_' + cmd + '_when_not_ready', False)
            desc = getattr(self, 'cmd_' + cmd + '_help', None)
            self.register_command(cmd, func, wnr, desc)
            for a in getattr(self, 'cmd_' + cmd + '_aliases', []):
                self.register_command(a, func, wnr)
        # G-Code coordinate manipulation
        self.absolutecoord = self.absoluteextrude = True
        self.base_position = [0.0, 0.0, 0.0, 0.0]
        self.last_position = [0.0, 0.0, 0.0, 0.0]
        self.homing_position = [0.0, 0.0, 0.0, 0.0]
        self.speed_factor = 1. / 60.
        self.extrude_factor = 1.
        self.move_transform = self.move_with_transform = None
        self.position_with_transform = (lambda: [0., 0., 0., 0.])
        # G-Code state
        self.need_ack = False
        self.toolhead = self.fan = self.extruder = None
        self.heaters = []
        self.speed = 25.0
        self.axis2pos = {'X': 0, 'Y': 1, 'Z': 2, 'E': 3}
    def register_command(self, cmd, func, when_not_ready=False, desc=None):
        if func is None:
            if cmd in self.ready_gcode_handlers:
                del self.ready_gcode_handlers[cmd]
            if cmd in self.base_gcode_handlers:
                del self.base_gcode_handlers[cmd]
            return
        if cmd in self.ready_gcode_handlers:
            raise error("gcode command %s already registered" % (cmd,))
        if not (len(cmd) >= 2 and not cmd[0].isupper() and cmd[1].isdigit()):
            origfunc = func
            func = lambda params: origfunc(self.get_extended_params(params))
        self.ready_gcode_handlers[cmd] = func
        if when_not_ready:
            self.base_gcode_handlers[cmd] = func
        if desc is not None:
            self.gcode_help[cmd] = desc
    def register_mux_command(self, cmd, key, value, func, desc=None):
        prev = self.mux_commands.get(cmd)
        if prev is None:
            self.register_command(cmd, self.cmd_mux, desc=desc)
            self.mux_commands[cmd] = prev = (key, {})
        prev_key, prev_values = prev
        if prev_key != key:
            raise error("mux command %s %s %s may have only one key (%s)" % (
                cmd, key, value, prev_key))
        if value in prev_values:
            raise error("mux command %s %s %s already registered (%s)" % (
                cmd, key, value, prev_values))
        prev_values[value] = func
    def set_move_transform(self, transform):
        if self.move_transform is not None:
            raise self.printer.config_error(
                "G-Code move transform already specified")
        self.move_transform = transform
        self.move_with_transform = transform.move
        self.position_with_transform = transform.get_position
    def stats(self, eventtime):
        return False, "gcodein=%d" % (self.bytes_read,)
    def get_status(self, eventtime):
        busy = self.is_processing_data
        return {'speed_factor': self.speed_factor * 60., 'busy': busy}
    def printer_state(self, state):
        if state == 'shutdown':
            if not self.is_printer_ready:
                return
            self.is_printer_ready = False
            self.gcode_handlers = self.base_gcode_handlers
            self.dump_debug()
            if self.is_fileinput:
                self.printer.request_exit('error_exit')
            return
        if state != 'ready':
            return
        self.is_printer_ready = True
        self.gcode_handlers = self.ready_gcode_handlers
        # Lookup printer components
        self.toolhead = self.printer.lookup_object('toolhead')
        if self.move_transform is None:
            self.move_with_transform = self.toolhead.move
            self.position_with_transform = self.toolhead.get_position
        extruders = kinematics.extruder.get_printer_extruders(self.printer)
        if extruders:
            self.extruder = extruders[0]
            self.toolhead.set_extruder(self.extruder)
        self.heaters = [ e.get_heater() for e in extruders ]
        self.heaters.append(self.printer.lookup_object('heater_bed', None))
        self.fan = self.printer.lookup_object('fan', None)
        if self.is_fileinput and self.fd_handle is None:
            self.fd_handle = self.reactor.register_fd(self.fd, self.process_data)
    def reset_last_position(self):
        self.last_position = self.position_with_transform()
    def dump_debug(self):
        out = []
        out.append("Dumping gcode input %d blocks" % (
            len(self.input_log),))
        for eventtime, data in self.input_log:
            out.append("Read %f: %s" % (eventtime, repr(data)))
        out.append(
            "gcode state: absolutecoord=%s absoluteextrude=%s"
            " base_position=%s last_position=%s homing_position=%s"
            " speed_factor=%s extrude_factor=%s speed=%s" % (
                self.absolutecoord, self.absoluteextrude,
                self.base_position, self.last_position, self.homing_position,
                self.speed_factor, self.extrude_factor, self.speed))
        logging.info("\n".join(out))
    # Parse input into commands
    args_r = re.compile('([A-Z_]+|[A-Z*/])')
    def process_commands(self, commands, need_ack=True):
        for line in commands:
            # Ignore comments and leading/trailing spaces
            line = origline = line.strip()
            cpos = line.find(';')
            if cpos >= 0:
                line = line[:cpos]
            # Break command into parts
            parts = self.args_r.split(line.upper())[1:]
            params = { parts[i]: parts[i+1].strip()
                       for i in range(0, len(parts), 2) }
            params['#original'] = origline
            if parts and parts[0] == 'N':
                # Skip line number at start of command
                del parts[:2]
            if not parts:
                # Treat empty line as empty command
                parts = ['', '']
            params['#command'] = cmd = parts[0] + parts[1].strip()
            # Invoke handler for command
            self.need_ack = need_ack
            handler = self.gcode_handlers.get(cmd, self.cmd_default)
            try:
                handler(params)
            except error as e:
                self.respond_error(str(e))
                self.reset_last_position()
                if not need_ack:
                    raise
            except:
                msg = 'Internal error on command:"%s"' % (cmd,)
                logging.exception(msg)
                self.printer.invoke_shutdown(msg)
                self.respond_error(msg)
                if not need_ack:
                    raise
            self.ack()
    m112_r = re.compile('^(?:[nN][0-9]+)?\s*[mM]112(?:\s|$)')
    def process_data(self, eventtime):
        # Read input, separate by newline, and add to pending_commands
        data = os.read(self.fd, 4096)
        self.input_log.append((eventtime, data))
        self.bytes_read += len(data)
        lines = data.split('\n')
        lines[0] = self.partial_input + lines[0]
        self.partial_input = lines.pop()
        pending_commands = self.pending_commands
        pending_commands.extend(lines)
        # Special handling for debug file input EOF
        if not data and self.is_fileinput:
            if not self.is_processing_data:
                self.request_restart('exit')
            pending_commands.append("")
        # Handle case where multiple commands pending
        if self.is_processing_data or len(pending_commands) > 1:
            if len(pending_commands) < 20:
                # Check for M112 out-of-order
                for line in lines:
                    if self.m112_r.match(line) is not None:
                        self.cmd_M112({})
            if self.is_processing_data:
                if len(pending_commands) >= 20:
                    # Stop reading input
                    self.reactor.unregister_fd(self.fd_handle)
                    self.fd_handle = None
                return
        # Process commands
        self.is_processing_data = True
        self.pending_commands = []
        self.process_commands(pending_commands)
        if self.pending_commands:
            self.process_pending()
        self.is_processing_data = False
    def process_pending(self):
        pending_commands = self.pending_commands
        while pending_commands:
            self.pending_commands = []
            self.process_commands(pending_commands)
            pending_commands = self.pending_commands
        if self.fd_handle is None:
            self.fd_handle = self.reactor.register_fd(self.fd, self.process_data)
    def process_batch(self, command):
        if self.is_processing_data:
            return False
        self.is_processing_data = True
        try:
            self.process_commands([command], need_ack=False)
        finally:
            if self.pending_commands:
                self.process_pending()
            self.is_processing_data = False
        return True
    def run_script_from_command(self, script):
        prev_need_ack = self.need_ack
        try:
            self.process_commands(script.split('\n'), need_ack=False)
        finally:
            self.need_ack = prev_need_ack
    def run_script(self, script):
        curtime = self.reactor.monotonic()
        for line in script.split('\n'):
            while 1:
                try:
                    res = self.process_batch(line)
                except:
                    break
                if res:
                    break
                curtime = self.reactor.pause(curtime + 0.100)
    # Response handling
    def ack(self, msg=None):
        if not self.need_ack or self.is_fileinput:
            return
        if msg:
            os.write(self.fd, "ok %s\n" % (msg,))
        else:
            os.write(self.fd, "ok\n")
        self.need_ack = False
    def respond(self, msg):
        if self.is_fileinput:
            return
        os.write(self.fd, msg+"\n")
    def respond_info(self, msg):
        logging.debug(msg)
        lines = [l.strip() for l in msg.strip().split('\n')]
        self.respond("// " + "\n// ".join(lines))
    def respond_error(self, msg):
        logging.warning(msg)
        lines = msg.strip().split('\n')
        if len(lines) > 1:
            self.respond_info("\n".join(lines))
        self.respond('!! %s' % (lines[0].strip(),))
        if self.is_fileinput:
            self.printer.request_exit('error_exit')
    # Parameter parsing helpers
    class sentinel: pass
    def get_str(self, name, params, default=sentinel, parser=str,
                minval=None, maxval=None, above=None, below=None):
        if name not in params:
            if default is self.sentinel:
                raise error("Error on '%s': missing %s" % (
                    params['#original'], name))
            return default
        try:
            value = parser(params[name])
        except:
            raise error("Error on '%s': unable to parse %s" % (
                params['#original'], params[name]))
        if minval is not None and value < minval:
            raise self.error("Error on '%s': %s must have minimum of %s" % (
                params['#original'], name, minval))
        if maxval is not None and value > maxval:
            raise self.error("Error on '%s': %s must have maximum of %s" % (
                params['#original'], name, maxval))
        if above is not None and value <= above:
            raise self.error("Error on '%s': %s must be above %s" % (
                params['#original'], name, above))
        if below is not None and value >= below:
            raise self.error("Error on '%s': %s must be below %s" % (
                params['#original'], name, below))
        return value
    def get_int(self, name, params, default=sentinel, minval=None, maxval=None):
        return self.get_str(name, params, default, parser=int,
                            minval=minval, maxval=maxval)
    def get_float(self, name, params, default=sentinel,
                  minval=None, maxval=None, above=None, below=None):
        return self.get_str(name, params, default, parser=float, minval=minval,
                            maxval=maxval, above=above, below=below)
    extended_r = re.compile(
        r'^\s*(?:N[0-9]+\s*)?'
        r'(?P<cmd>[a-zA-Z_][a-zA-Z_]+)(?:\s+|$)'
        r'(?P<args>[^#*;]*?)'
        r'\s*(?:[#*;].*)?$')
    def get_extended_params(self, params):
        m = self.extended_r.match(params['#original'])
        if m is None:
            # Not an "extended" command
            return params
        eargs = m.group('args')
        try:
            eparams = [earg.split('=', 1) for earg in eargs.split()]
            eparams = { k.upper(): v for k, v in eparams }
            eparams.update({k: params[k] for k in params if k.startswith('#')})
            return eparams
        except ValueError as e:
            raise error("Malformed command '%s'" % (params['#original'],))
    # Temperature wrappers
    def get_temp(self, eventtime):
        # Tn:XXX /YYY B:XXX /YYY
        out = []
        for i, heater in enumerate(self.heaters):
            if heater is not None:
                cur, target = heater.get_temp(eventtime)
                name = "B"
                if i < len(self.heaters) - 1:
                    name = "T%d" % (i,)
                out.append("%s:%.1f /%.1f" % (name, cur, target))
        if not out:
            return "T:0"
        return " ".join(out)
    def bg_temp(self, heater):
        if self.is_fileinput:
            return
        eventtime = self.reactor.monotonic()
        while self.is_printer_ready and heater.check_busy(eventtime):
            print_time = self.toolhead.get_last_move_time()
            self.respond(self.get_temp(eventtime))
            eventtime = self.reactor.pause(eventtime + 1.)
    def set_temp(self, params, is_bed=False, wait=False):
        temp = self.get_float('S', params, 0.)
        heater = None
        if is_bed:
            heater = self.heaters[-1]
        elif 'T' in params:
            index = self.get_int(
                'T', params, minval=0, maxval=len(self.heaters)-2)
            heater = self.heaters[index]
        elif self.extruder is not None:
            heater = self.extruder.get_heater()
        if heater is None:
            if temp > 0.:
                self.respond_error("Heater not configured")
            return
        print_time = self.toolhead.get_last_move_time()
        try:
            heater.set_temp(print_time, temp)
        except heater.error as e:
            raise error(str(e))
        if wait and temp:
            self.bg_temp(heater)
    def set_fan_speed(self, speed):
        if self.fan is None:
            if speed and not self.is_fileinput:
                self.respond_info("Fan not configured")
            return
        print_time = self.toolhead.get_last_move_time()
        self.fan.set_speed(print_time, speed)
    # G-Code special command handlers
    def cmd_default(self, params):
        if not self.is_printer_ready:
            self.respond_error(self.printer.get_state_message())
            return
        cmd = params.get('#command')
        if not cmd:
            logging.debug(params['#original'])
            return
        if cmd[0] == 'T' and len(cmd) > 1 and cmd[1].isdigit():
            # Tn command has to be handled specially
            self.cmd_Tn(params)
            return
        self.respond_info('Unknown command:"%s"' % (cmd,))
    def cmd_Tn(self, params):
        # Select Tool
        extruders = kinematics.extruder.get_printer_extruders(self.printer)
        index = self.get_int('T', params, minval=0, maxval=len(extruders)-1)
        e = extruders[index]
        if self.extruder is e:
            return
        self.run_script_from_command(self.extruder.get_activate_gcode(False))
        try:
            self.toolhead.set_extruder(e)
        except homing.EndstopError as e:
            raise error(str(e))
        self.extruder = e
        self.reset_last_position()
        self.extrude_factor = 1.
        self.base_position[3] = self.last_position[3]
        self.run_script_from_command(self.extruder.get_activate_gcode(True))
    def cmd_mux(self, params):
        key, values = self.mux_commands[params['#command']]
        if None in values:
            key_param = self.get_str(key, params, None)
        else:
            key_param = self.get_str(key, params)
        if key_param not in values:
            raise error("The value '%s' is not valid for %s" % (key_param, key))
        values[key_param](params)
    all_handlers = [
        'G1', 'G4', 'G28', 'M18', 'M400',
        'G20', 'M82', 'M83', 'G90', 'G91', 'G92', 'M114', 'M220', 'M221',
        'SET_GCODE_OFFSET', 'M206',
        'M105', 'M104', 'M109', 'M140', 'M190', 'M106', 'M107',
        'M112', 'M115', 'IGNORE', 'GET_POSITION',
        'RESTART', 'FIRMWARE_RESTART', 'ECHO', 'STATUS', 'HELP']
    # G-Code movement commands
    cmd_G1_aliases = ['G0']
    def cmd_G1(self, params):
        # Move
        try:
            for axis in 'XYZ':
                if axis in params:
                    v = float(params[axis])
                    pos = self.axis2pos[axis]
                    if not self.absolutecoord:
                        # value relative to position of last move
                        self.last_position[pos] += v
                    else:
                        # value relative to base coordinate position
                        self.last_position[pos] = v + self.base_position[pos]
            if 'E' in params:
                v = float(params['E']) * self.extrude_factor
                if not self.absolutecoord or not self.absoluteextrude:
                    # value relative to position of last move
                    self.last_position[3] += v
                else:
                    # value relative to base coordinate position
                    self.last_position[3] = v + self.base_position[3]
            if 'F' in params:
                speed = float(params['F']) * self.speed_factor
                if speed <= 0.:
                    raise error("Invalid speed in '%s'" % (params['#original'],))
                self.speed = speed
        except ValueError as e:
            raise error("Unable to parse move '%s'" % (params['#original'],))
        try:
            self.move_with_transform(self.last_position, self.speed)
        except homing.EndstopError as e:
            raise error(str(e))
    def cmd_G4(self, params):
        # Dwell
        if 'S' in params:
            delay = self.get_float('S', params, minval=0.)
        else:
            delay = self.get_float('P', params, 0., minval=0.) / 1000.
        self.toolhead.dwell(delay)
    def cmd_G28(self, params):
        # Move to origin
        axes = []
        for axis in 'XYZ':
            if axis in params:
                axes.append(self.axis2pos[axis])
        if not axes:
            axes = [0, 1, 2]
        homing_state = homing.Homing(self.toolhead)
        if self.is_fileinput:
            homing_state.set_no_verify_retract()
        try:
            homing_state.home_axes(axes)
        except homing.EndstopError as e:
            raise error(str(e))
        for axis in homing_state.get_axes():
            self.base_position[axis] = self.homing_position[axis]
        self.reset_last_position()
    cmd_M18_aliases = ["M84"]
    def cmd_M18(self, params):
        # Turn off motors
        self.toolhead.motor_off()
    def cmd_M400(self, params):
        # Wait for current moves to finish
        self.toolhead.wait_moves()
    # G-Code coordinate manipulation
    def cmd_G20(self, params):
        # Set units to inches
        self.respond_error('Machine does not support G20 (inches) command')
    def cmd_M82(self, params):
        # Use absolute distances for extrusion
        self.absoluteextrude = True
    def cmd_M83(self, params):
        # Use relative distances for extrusion
        self.absoluteextrude = False
    def cmd_G90(self, params):
        # Use absolute coordinates
        self.absolutecoord = True
    def cmd_G91(self, params):
        # Use relative coordinates
        self.absolutecoord = False
    def cmd_G92(self, params):
        # Set position
        offsets = { p: self.get_float(a, params)
                    for a, p in self.axis2pos.items() if a in params }
        for p, offset in offsets.items():
            if p == 3:
                offset *= self.extrude_factor
            self.base_position[p] = self.last_position[p] - offset
        if not offsets:
            self.base_position = list(self.last_position)
    cmd_M114_when_not_ready = True
    def cmd_M114(self, params):
        # Get Current Position
        p = [lp - bp for lp, bp in zip(self.last_position, self.base_position)]
        p[3] /= self.extrude_factor
        self.respond("X:%.3f Y:%.3f Z:%.3f E:%.3f" % tuple(p))
    def cmd_M220(self, params):
        # Set speed factor override percentage
        value = self.get_float('S', params, 100., above=0.) / (60. * 100.)
        self.speed_factor = value
    def cmd_M221(self, params):
        # Set extrude factor override percentage
        new_extrude_factor = self.get_float('S', params, 100., above=0.) / 100.
        last_e_pos = self.last_position[3]
        e_value = (last_e_pos - self.base_position[3]) / self.extrude_factor
        self.base_position[3] = last_e_pos - e_value * new_extrude_factor
        self.extrude_factor = new_extrude_factor
    cmd_SET_GCODE_OFFSET_help = "Set a virtual offset to g-code positions"
    def cmd_SET_GCODE_OFFSET(self, params):
        for axis, pos in self.axis2pos.items():
            if axis in params:
                offset = self.get_float(axis, params)
            elif axis + '_ADJUST' in params:
                offset = self.homing_position[pos]
                offset += self.get_float(axis + '_ADJUST', params)
            else:
                continue
            delta = offset - self.homing_position[pos]
            self.last_position[pos] += delta
            self.base_position[pos] += delta
            self.homing_position[pos] = offset
    def cmd_M206(self, params):
        # Offset axes
        offsets = { self.axis2pos[a]: self.get_float(a, params)
                    for a in 'XYZ' if a in params }
        for p, offset in offsets.items():
            self.base_position[p] -= self.homing_position[p] + offset
            self.homing_position[p] = -offset
    # G-Code temperature and fan commands
    cmd_M105_when_not_ready = True
    def cmd_M105(self, params):
        # Get Extruder Temperature
        self.ack(self.get_temp(self.reactor.monotonic()))
    def cmd_M104(self, params):
        # Set Extruder Temperature
        self.set_temp(params)
    def cmd_M109(self, params):
        # Set Extruder Temperature and Wait
        self.set_temp(params, wait=True)
    def cmd_M140(self, params):
        # Set Bed Temperature
        self.set_temp(params, is_bed=True)
    def cmd_M190(self, params):
        # Set Bed Temperature and Wait
        self.set_temp(params, is_bed=True, wait=True)
    def cmd_M106(self, params):
        # Set fan speed
        self.set_fan_speed(self.get_float('S', params, 255., minval=0.) / 255.)
    def cmd_M107(self, params):
        # Turn fan off
        self.set_fan_speed(0.)
    # G-Code miscellaneous commands
    cmd_M112_when_not_ready = True
    def cmd_M112(self, params):
        # Emergency Stop
        self.printer.invoke_shutdown("Shutdown due to M112 command")
    cmd_M115_when_not_ready = True
    def cmd_M115(self, params):
        # Get Firmware Version and Capabilities
        software_version = self.printer.get_start_args().get('software_version')
        kw = {"FIRMWARE_NAME": "Klipper", "FIRMWARE_VERSION": software_version}
        self.ack(" ".join(["%s:%s" % (k, v) for k, v in kw.items()]))
    cmd_IGNORE_when_not_ready = True
    cmd_IGNORE_aliases = ["G21", "M110", "M21"]
    def cmd_IGNORE(self, params):
        # Commands that are just silently accepted
        pass
    cmd_GET_POSITION_when_not_ready = True
    def cmd_GET_POSITION(self, params):
        if self.toolhead is None:
            self.cmd_default(params)
            return
        kin = self.toolhead.get_kinematics()
        steppers = kin.get_steppers()
        mcu_pos = " ".join(["%s:%d" % (s.get_name(), s.get_mcu_position())
                            for s in steppers])
        stepper_pos = " ".join(
            ["%s:%.6f" % (s.get_name(), s.get_commanded_position())
             for s in steppers])
        kinematic_pos = " ".join(["%s:%.6f"  % (a, v)
                                  for a, v in zip("XYZE", kin.calc_position())])
        toolhead_pos = " ".join(["%s:%.6f" % (a, v) for a, v in zip(
            "XYZE", self.toolhead.get_position())])
        gcode_pos = " ".join(["%s:%.6f"  % (a, v)
                              for a, v in zip("XYZE", self.last_position)])
        base_pos = " ".join(["%s:%.6f"  % (a, v)
                             for a, v in zip("XYZE", self.base_position)])
        homing_pos = " ".join(["%s:%.6f"  % (a, v)
                               for a, v in zip("XYZ", self.homing_position)])
        self.respond_info(
            "mcu: %s\n"
            "stepper: %s\n"
            "kinematic: %s\n"
            "toolhead: %s\n"
            "gcode: %s\n"
            "gcode base: %s\n"
            "gcode homing: %s" % (
                mcu_pos, stepper_pos, kinematic_pos, toolhead_pos,
                gcode_pos, base_pos, homing_pos))
    def request_restart(self, result):
        if self.is_printer_ready:
            self.respond_info("Preparing to restart...")
            self.toolhead.motor_off()
            print_time = self.toolhead.get_last_move_time()
            for heater in self.heaters:
                if heater is not None:
                    heater.set_temp(print_time, 0.)
            if self.fan is not None:
                self.fan.set_speed(print_time, 0.)
            self.toolhead.dwell(0.500)
            self.toolhead.wait_moves()
        self.printer.request_exit(result)
    cmd_RESTART_when_not_ready = True
    cmd_RESTART_help = "Reload config file and restart host software"
    def cmd_RESTART(self, params):
        self.request_restart('restart')
    cmd_FIRMWARE_RESTART_when_not_ready = True
    cmd_FIRMWARE_RESTART_help = "Restart firmware, host, and reload config"
    def cmd_FIRMWARE_RESTART(self, params):
        self.request_restart('firmware_restart')
    cmd_ECHO_when_not_ready = True
    def cmd_ECHO(self, params):
        self.respond_info(params['#original'])
    cmd_STATUS_when_not_ready = True
    cmd_STATUS_help = "Report the printer status"
    def cmd_STATUS(self, params):
        msg = self.printer.get_state_message()
        if self.is_printer_ready:
            self.respond_info(msg)
        else:
            self.respond_error(msg)
    cmd_HELP_when_not_ready = True
    def cmd_HELP(self, params):
        cmdhelp = []
        if not self.is_printer_ready:
            cmdhelp.append("Printer is not ready - not all commands available.")
        cmdhelp.append("Available extended commands:")
        for cmd in sorted(self.gcode_handlers):
            if cmd in self.gcode_help:
                cmdhelp.append("%-10s: %s" % (cmd, self.gcode_help[cmd]))
        self.respond_info("\n".join(cmdhelp))