The "Watchdog" board, or air compressor controller, controls:
- Power to the compressor.
- Whether the output valve is open or closed.
The controller simply controls power to the compressor. Whether it actually runs or not is determined autonomously by the compressor itself, based on the air pressure in the tank, just like any normal compressor.
The controller accepts requests to turn on the compressor from the following sources:
- Physical buttons on the controller.
- Our automation system, over the network. In practice, such requests are made whenever the LASER cutters are in use, or a blast gate needs to be activated.
The controller monitors whether the compressor is actually running (not simply powered on) and checks for the follow alarm conditions:
- The compressor has been running non-stop for too long.
- The compressor has been running with too high a duty cycle for a long time.
The compressor will be turned on, and the output valve opened, if any source has requested it, and there is no active alarm condition.
When an alarm condition is raised, the compressour is turned off, the output valve is closed, and any request for the compressor to be on is forgotten.
An alarm condition is automatically cancelled after a certain time. There is no way to manually cancel the alarm condition.
If you want to use air in the wood shop, press the green button. Once you're done, press the red button to cancel the request. Your request will also be automatically cancelled after 1 hour; simply press the green button again if you need air for longer.
The buttons only request or cancel the local request for air. They do not effect, override, or cancel any request from the automation system. There is no way to locally force the compressor to turn off, or to reset alarms.
Blue LED (Controller power):
- Always on if power is present.
Yellow LED (Connected):
- Off: WiFi disconnected.
- Flashing: WiFi connected, Automation/MQTT disconnected.
- On: WiFi & MQTT both connected.
Green LED (Access):
- Off: Compressor power is off, valve should be open.
- Flashing: Alarm: Flash count is alarm type.
- On: Compressor power is on, valve should be closed.
Alarm flash counts: 2: Max runtime exceeded. 3: Duty cycle exceeded. 4: Max and duty cycle exceeded.
Orange LED (Sense):
- Off: Compressor motor running.
- On: Compressor motor running.
Green (Relay):
- The compressor power is on.
Green (Valve Open):
- The compressor valve has reached the open position. It will take a few seconds for this LED to light after the compressor is turned on. The LED lights only after the valve reaches the fully open position.
Red (Valve Closed):
- The compressor valve has reached the closed position. It will take a few seconds for this LED to light after the compressor is turned off. The LED lights only after the valve reaches the fully closed position.
Any alarm condition indicates a problem that should be actively addressed. All alarms indicate that the compressor is running outside of its specifications. It is likely that if the controller did not automatically turn off the compressor, it would overheat and fail. Assuming there is no air leak, an alarm condition indicates that you should reduce air demand by lowering air pressure at the equipment, or by using less equipment at the same time.
The compressor motor has been running non-stop for more than the configured time limit. This indicates that the compressor outright cannot keep up with the demand for air no matter how much it runs.
The compressor motor has been running for more that the configured percentage of time over a configured time window. This indicates that compressor is (perhaps only just) able to keep up with the demand for air, but the demand is higher than expected, and higher than allowed by compressor specification.
The following situations may trigger an alarm:
- Too much concurrent usage. For example:
- Both LASERs at high air assist pressure.
- One LASER plus some medium use of the wood shop air hoses.
- One LASER at very high air assist pressure.
- High use of the wood shop air hoses.
- A leak in the air lines.
Either alarm may be caused by any condition; it simply boils down to how excessive the demand is, and how long the demand lasts, vs. the compressor's capabilities.
The controller automatically cancels all alarms after a configurable cooldown period following the most recent time any alarm was triggered. There is not way for a user to override this; you must simply wait for the cooldown period.
Once the alarm condition has been cancelled, a new request must be made before the controller will turn on the compressor again. This could be by:
- Placing an RFID onto a piece of equipment. Note that this must be a fresh read of the RFID; simply leaving the RFID on the equipment is not enough.
- Pressing the request button on the control panel. Again, this will only be registered if it happens after the alarm condition is cancelled.
The controller software has many configuration option, such as:
- WiFi parameters.
- MQTT parameters.
- Current sensor configuration.
- Alarm configuration.
These values are not baked into the software. Rather, they're stored in flash or EEPROM on the device. These values can be edited using a web browser when the device is in "wificonfig" mode.
The alarm-related configuration values are currently:
- Max time: 20 (minutes).
- Duty Cycle: 50 (%).
- Duty Cycle Window: 60 (minutes).
- Alarm Cooldown (auto-reset time): 30 (minutes).
- On-Button Timeout: 60 (minutes).
- On-MQTT Timeout: 10 (minutes).
IMPORTANT: Do not disassemble or reconfigure the compressor controller without prior approval from a quorum of the FCCH board.
The controller will enter wificonfig mode when it's first powered on if the configuration data is missing WiFi connection information.
Otherwise, to enter wificonfig mode, press the GPIO0 button on the controller circuit board for over 30 seconds, then release it. The device will start a WiFi access point, probably with SSID of "ESP". Connect to this using a phone or computer. Once connected, open http://192.168.4.1/ using a web-browser. Make sure to save your changed before rebooting. When the reboot button is clicked, the device wil reboot and enter regular operation.
To access the GPIO 0 button, you will need to open the controller box. The buttons are on the under-side of the PCB, i.e. between the PCB and the box panel. You can use a non-metallic (e.g. plastic) stick/spatula/similar to slide under the PCB and press the button; this is by far the simplest. Or in the worst case, unscrew the PCB from the box panel.
