Feature: Environment Manager¶

Concept¶

The Environment Manager turns an enclosed MMU into a filament dryer. It pairs a humidity/temperature sensor with one or more heaters and runs a managed drying cycle: pick a target temperature and time (or let Happy Hare recommend both from the filament types already loaded), and it heats, tracks progress, and shuts itself off - optionally venting warm humid air partway through, and gently rotating spools if an eSpooler is fitted so a respooled filament end doesn't just sit against one hot side of the spool the whole time.

Two hardware layouts are supported:

• Single heater / shared enclosure - one heater and one environment sensor for the whole enclosure. This is the common case, and everything on this page defaults to it.
• Per-gate heaters - each gate has its own heater and sensor (for example, the modular EMU design, where every gate is its own small enclosure). A basic power-management queue limits how many heaters run simultaneously so you don't trip a PSU. Configuring both a single heater/sensor and per-gate lists at the same time is a config error - pick one.

Hardware Setup¶

Both pieces are enabled under MMU Features / Additions, and each gets its own config submenu once switched on.

Environment sensor¶

Produces, inside the unit's [mmu_unit ...] section in mmu_hardware.cfg:

environment_sensor : temperature_sensor unit0_Env

A per-gate design (MMU_HAS_PER_GATE_ENV_SENSORS, only available on hardware with a per-gate MCU) repeats the same prompts once per gate instead, and produces a comma-separated list:

environment_sensors : temperature_sensor unit0_Env0, temperature_sensor unit0_Env1, ...

Heater(s)¶

Produces, alongside the sensor key in the same [mmu_unit ...] section:

filament_heater : heater_generic unit0_heater

or, per-gate:

filament_heaters       : heater_generic unit0_heater0, heater_generic unit0_heater1, ...
max_concurrent_heaters : 1

Parameter Setup¶

The heater controller's own tuning constants live in mmu_parameters.cfg, alongside the drying-recipe table:

heater_max_temp             : 65     # Absolute ceiling; drying never targets above this regardless of drying_data
heater_default_dry_temp     : 45     # Fallback drying temperature for an unrecognised or empty gate
heater_default_dry_time     : 300    # Fallback drying time in minutes
heater_default_dry_humidity : 25     # Default humidity % goal - drying ends early if reached
heater_vent_macro           : _MMU_VENT  # Name of a macro to call periodically during drying (see Tuning below)
heater_vent_interval        : 0      # Minutes between vent-macro calls, 0 = disabled
heater_rotate_interval      : 5      # Minutes between spool-rotation bursts, requires eSpooler and explicit GATES

drying_data : { 'pla': (45, 300), 'pla+': (55, 300), 'petg': (60, 300), 'tpu': (55, 300), 'abs': (70, 300),
                'abs+': (75, 300), 'asa': (65, 300), 'nylon': (75, 600), 'pc': (75, 600), 'pva': (75, 600),
                'hips': (75, 600) }

drying_data maps a material name (matched case-insensitively) to (temperature_C, time_minutes). Starting a drying cycle without an explicit TEMP/TIMER looks up each selected gate's assigned material here and uses the lowest recommended temperature and longest recommended time across them, capped at heater_max_temp; a gate with no material assigned, or that's empty, falls back to heater_default_dry_temp/heater_default_dry_time. Extend the table with your own materials freely - it's a plain dict, and MMU_HEATER DRYING_DATA=1 dumps whatever is currently configured. A smaller, illustrative table showing just the shape of it:

drying_data: "{'PLA': (45, 240), 'PETG': (55, 300), 'NYLON': (65, 480)}"

• Values are (temperature_C, time_minutes).
• A material missing from the table falls back to heater_default_dry_temp and heater_default_dry_time, same as an unrecognised material would.

Commands¶

MMU_HEATER                                     # Status report - heater state, or drying cycle progress
MMU_HEATER TEMP=50                             # Set/adjust heater temperature directly
MMU_HEATER DRY=1                               # Start a drying cycle, temp/time recommended from drying_data
MMU_HEATER DRY=1 TEMP=50 TIMER=240 HUMIDITY=12  # ...or override any of them
MMU_HEATER STOP=1                              # Stop the current drying cycle (or turn the heater off)
MMU_HEATER DRYING_DATA=1                       # List the configured drying-data table

Full parameter reference: MMU_HEATER.

With per-gate heaters, everything above takes a GATES= list (defaulting to all non-empty gates if omitted):

MMU_HEATER DRY=1 GATES=0,2,3       # Dry only these gates (subject to the concurrency cap)
MMU_HEATER TEMP=45 GATES=0,1       # Raw heater control for specific gates
MMU_HEATER STOP=1 GATES=1,3        # Cancel only these gates, leaving the rest of the cycle running

If more gates are selected than max_concurrent_heaters allows, the extra gates queue and start automatically as active ones finish - the overall cycle can take longer than any single gate's own timer as a result. TEMP= on a gate behaves according to that gate's current state: queued - only the stored target changes, the heater doesn't turn on yet; active - the heater updates immediately; not part of the current cycle - it's just set immediately, same as raw single-heater control.

MMU_HEATER STOP=1 GATES=1,3 cancelling only some gates behaves according to each gate's current state too: an active gate has its heater turned off immediately and is marked done; a queued gate is simply removed from the queue and marked done, without ever having its heater turned on. If cancelling leaves no gates still running or queued, the overall drying cycle ends automatically.

A plain MMU_HEATER with no drying cycle running just reports that:

MMU_HEATER

Not in drying cycle and heater is off

A status report while drying looks like this (single-heater mode):

MMU is in filament drying cycle:
Drying filaments in gates: 1,2,6,7
Cycle time: 4 hours (remaining: 3 hours 46 minutes)
Target humidity: 25.0% (current: 63.6%)
Drying temp: 55.0°C (current: 48.3°C)
Venting operational (running macro _MMU_VENT every 15 minutes, next in 11 minutes)
Spool rotation enabled (running every 5 minutes, next in <1 minute)

or, per-gate:

MMU is in filament drying cycle:
Drying filaments in gates: 1,2,5,6,7,8
Per-gate dryer mode (max concurrent heaters: 3). Humidty target 25.0%
Gate 1: (timer complete, final humidity: 22.3%)
Gate 2: Drying ABS 27.3°C (target 65.0°C), humidity 62.9%, 1 hour 1 minute remaining
Gate 5: Drying PLA 27.3°C (target 45.0°C), humidity 63.1%, 1 hour 1 minute remaining
Gate 6: Drying PETG 27.3°C (target 55.0°C), humidity 63.6%, 13 minutes remaining
Gate 7: (queued waiting for heater slot, target 45.0°C)
Gate 8: (queued waiting for heater slot, target 65.0°C)

Printer variables exposed¶

drying_state - a per-gate list of '' | queued | active | complete | canceled. See Per-gate arrays merged across every unit in the printer variable reference.

Tuning¶

Venting¶

A vent macro runs periodically only while a drying cycle is active, to flush warm humid air from the enclosure and speed up drying. Many designs have a passive vent; some use a servo-actuated flap and an extraction fan - the macro is entirely up to you. Set heater_vent_macro and heater_vent_interval (minutes, 0 disables it), or override the interval for a single cycle with MMU_HEATER DRY=1 VENT_INTERVAL=10. The macro should open the vent and queue its own delayed close rather than blocking with M400 - a ready-to-adapt skeleton using delayed_gcode for exactly that ships as _MMU_VENT in config/macros/mmu_heater_vent.cfg. In per-gate mode, the macro is called with GATES=<currently active gates>; in single-heater mode it's called with no arguments. The shipped skeleton looks like this:

[gcode_macro _MMU_VENT]
description: Simple reference MMU enclosure venting control

gcode:
    {% set gates = (params.GATES | default('')).split(',') | map('trim') | list %}

    {% if gates == [''] %}

        MMU_LOG MSG="Opening MMU vent..."
        # Add logic to operate servo to open vent here, perhaps also turn on/up extraction fan

    {% else %}

        MMU_LOG MSG="Opening MMU vent to dry filaments in gates: {", ".join(gates)}..."
        {% for gate in gates %}
            # Open vent servo_{gate}
        {% endfor %}

    {% endif %}

    # Close the vent after 10 seconds
    UPDATE_DELAYED_GCODE ID=_MMU_VENT_CLOSE DURATION=10


[delayed_gcode _MMU_VENT_CLOSE]
gcode:
    MMU_LOG MSG="Closing MMU vent..."
    # Add logic to operate servo to close vent here, perhaps also turn off/down extraction fan

The delayed_gcode/UPDATE_DELAYED_GCODE pairing is the point of the example: it lets the macro return immediately after opening the vent instead of blocking the toolhead with M400 while it waits to close again.

Spool rotation¶

If an eSpooler is fitted, a drying cycle can periodically nudge each spool a short distance in the rewind direction - just enough to stop a respooled filament end from baking against one point of contact for hours. Start it with MMU_HEATER DRY=1 ROTATE=1 GATES=1,3 - GATES must be given explicitly whenever ROTATE=1 is used. Rotation only actually happens for gates that are genuinely empty at the moment the timer fires (filament removed from the MMU inlet and secured to the spool) - Happy Hare re-checks this every heater_rotate_interval minutes rather than only once at the start, so you can safely unload a gate and secure it mid-cycle. If a gate passed to GATES= isn't empty yet when the cycle starts, Happy Hare warns about it immediately rather than staying silent until the first rotation tick - drying still proceeds normally, since a loaded gate simply can't rotate until it's cleared. It uses exactly the same power and duration as an ordinary rewind burst (espooler_rewind_burst_power/espooler_rewind_burst_duration) - there's no separate "rotate" setting to tune.

Choosing a temperature/time by hand¶

If your slicer's filament isn't in drying_data, either add an entry (it's a plain dict you can extend) or pass TEMP=/TIMER= explicitly for that cycle. HUMIDITY= ends a cycle as soon as the sensor reports at or below the target, which is usually a better stopping point than a fixed timer if your sensor supports humidity at all.

Troubleshooting¶

• Humidity always reports as missing - the sensor chip may not support humidity (some report temperature only), or the humidity reading isn't recognised. Drying still runs on the timer; humidity-based early termination just won't trigger.
• Venting never runs - heater_vent_macro is blank, or heater_vent_interval is 0. If it's configured and still not firing, check the console and log for macro errors.
• Drying takes longer than expected in per-gate mode - gates queue when max_concurrent_heaters is smaller than the number of gates you asked for; total wall-clock time is the sum of each queued gate's own timer, not the longest one.
• Rotation never happens - eSpooler isn't fitted, ROTATE=1 wasn't specified, or the gate genuinely wasn't empty (filament end secured to the spool) at the moment a rotation was due.
• No MMU heater configured error - filament_heater/filament_heaters is empty; the manager needs at least one heater object configured before MMU_HEATER will do anything.

See also¶

• Command Reference: MMU_HEATER
• Feature: eSpooler - the mechanism spool rotation reuses
• Printer Variables: per-gate arrays for the drying_state field