Overview
The AirMASTER FORM is a microprocessor-based compressor controller manufactured by CMC NV. It manages all compressor operating states, provides real-time parameter monitoring, displays faults and maintenance reminders, and supports optional networking and remote monitoring via RS485 Modbus, IoT (Ethernet / TCP-IP), or fieldbus modules.
Hardware
Keypad
The FORM front panel has three command buttons (START, STOP, RESET), four navigation keys (ENTER, ▲ Up, ▼ Down, ESCAPE), and a graphic display. On touch-screen versions the same actions can be performed by touching the on-screen buttons.
| Button | Function |
|---|---|
| START (green) | Start the compressor |
| STOP (red) | Stop the compressor (normal unloaded stop) |
| RESET | Acknowledge and reset a resolved alarm or fault. Press and hold the button briefly to clear the fault from memory. |
| ENTER | Open the menu from the Home screen, enter a selected tab or submenu, and confirm a selection or value |
| ▲ (Up arrow) | Move to the previous tab or item / increase a value |
| ▼ (Down arrow) | Move to the next tab or item / decrease a value |
| ESCAPE | Step back one level, exit an edit without saving, and return toward the Home screen |
Status Indicators (LEDs)
| Indicator | Meaning |
|---|---|
| Power | On = controller powered. Off = controller not powered. |
| Motor / Run | Off = motor not running. Slow flash = running or in a start sequence. On = running loaded. |
| Maintenance | On = maintenance required. Off = none due. |
| Alarm | Slow flash = warning active (A:…). Fast flash = immediate-stop active (E:…). |
Graphic Display
The Home screen is the default view after power-up, and the display returns to it after a period of no keypad use (set by the Logout Time). Each preset Home screen shows the compressor's key live values: delivery pressure, outlet temperature, percent load, operating status, and any active-function icons. A status toolbar runs along the top of the screen and a navigation toolbar along the bottom. After about 60 seconds of no use the backlight dims until a key is pressed or the screen is touched.
Active-function icons in the status toolbar flag conditions such as locked/unlocked access, service due, warning, fault, drain valve, remote control, fan, automatic restart, run schedule, IoT module, and clone key. If more icons are active than will fit, they collapse behind a "<<" symbol; selecting it expands them.
User Account Levels
The FORM supports multiple access levels. Operators can view operating data and acknowledge alarms. Items above operator level are either hidden or shown as read-only, and service or configuration parameters require an authorized service account. Contact South-Tek if service-level access is needed.
Menu Navigation
After power-up the controller shows the Home screen. From there you reach every parameter through a set of menu tabs.
- Open the menu. From the Home screen, press ENTER (or the Menu button in the navigation toolbar) to enter the menu tabs.
- Move between tabs. The menu tabs are arranged in a continuous loop. Use ▲ and ▼ to move between them. Press ESCAPE to return to the Home screen.
- Open a tab. With a tab highlighted, press ENTER to open it. The first item in the tab is highlighted.
- Move between items. Items are listed vertically in a continuous loop. Use ▲ and ▼ to move between them, or touch the item directly on a touch-screen unit. Items with a submenu show an enter indicator; press ENTER to open the submenu.
- Edit a value. For an editable item, press ENTER to open the edit popup. Use ▲ and ▼ to change the value or selection; press and hold to change faster. Press ENTER to confirm, or ESCAPE to exit without saving.
- Back out. Press ESCAPE to step back one level. Pressing ESCAPE from a tab returns you to the Home screen.
Menu Tabs
The FORM groups parameters into numbered menu tabs. The tabs available depend on the model and installed options; service and configuration tabs require an authorized account.
| Tab | Contents |
|---|---|
| P00 — User | Home and main operating values |
| P01 — Service Timers | Maintenance countdown timers per component |
| P02 — Utilisation | Running hours and load / utilisation counters |
| P03 — Error Log | Active and historical fault / alarm log |
| P04 — Event Log | Logged operating events |
| P05 — Service Provider | Service provider contact information |
| P06 — Controller Data | Serial number, software version and ID, network / IoT data |
| P07 — Asset Data | Equipment / asset identification data |
| P08 — Graph | Trend graph for pressure and temperature (up to one month of data) |
| P09 — Access | User account / access level entry |
| P10 / P11 / P12 — Settings 1, 2, 3 | Equipment setup parameters (service access required) |
| P13 — VSD Settings | Variable-speed drive parameters (VSD models) |
| P14 — Motor Protection | Motor protection thresholds |
| P15 — Inhibits | Start / load inhibit conditions |
| P16 / P17 — Warning & Immediate-Stop Alarms | Warning-alarm and immediate-stop alarm thresholds |
| P18 / P19 — I/O & Sensor Config | Digital / analog I/O and sensor configuration |
| P20 — Diagnostics | Live diagnostic values and I/O status |
| P21 — Run Schedule | Scheduled start / stop programming |
| P22 / P23 — Modbus Fan / VSD Info | Modbus-driven fan and VSD information |
| P24 / P25 — IO Extension & IO Sensor Config | IO extension module and its sensor configuration |
| P26 — RS485 Extension | RS485 / Modbus extension settings |
| P27 — IoT Settings | IoT module settings, MAC address, and IP configuration |
Operating States
| Phase | State | What is happening |
|---|---|---|
| Stopped | Power-Up Initialisation | Controller is powering up and initialising. |
| Stopped | Start Inhibit | Controller checks start-inhibit conditions. If an inhibit exists, the start is blocked and an inhibit message is displayed. |
| Stopped | Ready to Start | Energised, no active faults, awaiting a start command. |
| Stopped | Fault / Immediate Stop | Stopped by a protective (immediate-stop) alarm, or by the Emergency Stop button. The condition must be resolved and reset before restarting. |
| Started | Run Inhibit / Vent Time | After a start or a motor stop, a vent time runs and internal pressure must vent before the motor starts. A run inhibit sends the unit to Standby. |
| Started | Standby | Started but the motor is stopped. The unit automatically starts and loads when pressure falls to the Load setpoint (or when the inhibit clears). |
| Running | Motor Start | Main motor starting in a star-delta sequence (or VSD ramp). |
| Running | Load Inhibit Time | Loading is held off for a set time after the motor start to let motor speed stabilise. |
| Running · Loaded | On Load | Load relay energised; the compressor is producing air. It unloads at the Unload setpoint or on a remote offload command. |
| Running | Reload Inhibit Time | After unloading, reloading is held off until this timer expires. |
| Running | Off-Load Run Time | Running unloaded. If it runs unloaded for the Off-Load Run Time, the motor stops to Standby. |
| Running | Stop Run Time | On a stop command the unit unloads first, then the motor runs for the Stop Run Time before stopping. |
The diagram below shows the same sequence as the controller's state diagram, including the timed intermediate states, grouped under the STOPPED, STARTED, RUNNING, and LOADED conditions.
Control Modes
Local Control
The compressor is started and stopped using the START and STOP buttons on the controller panel. This is the default mode.
Remote / Automatic Control
When configured for remote operation, the compressor can be started and stopped via digital input signals (remote start/stop), Modbus RS485 commands, or IoT remote messages. The automatic restart parameter (disabled by default) allows the compressor to restart automatically after a power interruption.
Maintenance Warnings
The AirMASTER FORM displays maintenance reminders when a component reaches its service interval. The compressor continues running while maintenance warnings are active — the warnings remain on screen until manually reset.
Optional Modules
| Module | Function |
|---|---|
| RS485 / Modbus RTU | Fieldbus communication (Airbus485 proprietary or Modbus RTU slave/master). Enables integration with building management systems and SCADA. |
| IoT (Ethernet / TCP-IP) | Web browser monitoring over Ethernet. Provides Health, Performance, Custom, and Events dashboard pages. Supports remote start/stop flagging. Automatically syncs controller timestamp if internet-connected. |
| IO Extension | Additional analog and digital I/O for expanded sensor inputs (inlet vacuum, oil temperature, delivery temperature, oil pressure, oil filter differential, cooler approach temperatures). |
| Fieldbus Network Cards | Optional cards for Profibus, DeviceNet, EtherNet/IP, and other industrial protocols. |
Related Articles
- Compressor Operation - Start, Load/Unload & Stop
- Troubleshooting Guide
- Full AirMASTER Controller Manual