This article covers the touchscreen controller for the N2-GEN™ CPi-Plus & CPx-Plus Series, including the Home screen, starting and stopping the generator, trending graphs, the password-protected Menu, and all available settings. Optional features — including data logging, Ethernet/Modbus communications, Duplex, and Staging — are covered at the end of this article and only apply to units ordered with those options.
Home Screen
The Home screen is the default view after powering on. It displays system status, nitrogen purity setpoint, nitrogen storage tank pressure (and purity if an O2 sensor is installed), and cumulative run hours. From the Home screen, the user can start and stop the generator, navigate to the Graphs screen, and access the Alarms button if any alarms are active.
Run hours are displayed in the upper right corner of the Home screen below the current time and date. Run hours accumulate only when the generator is actively producing nitrogen — Standby time is excluded.
Starting & Stopping
The generator is started and stopped using the Start/Stop button located in the upper left corner of the Home screen.
- When the button is green, the generator is On and running (or in Standby).
- When the button is red, the generator is Stopped.
Press the Start/Stop button to toggle between states. When the generator is running, it automatically cycles through the adsorption beds to fill the nitrogen storage tank. When the tank reaches the cut-out pressure it enters Standby, pausing nitrogen production. When the tank pressure drops to the cut-in pressure, the system automatically restarts.
For a normal shutdown, first close the nitrogen-to-process valve on the storage tank output, then press the Start/Stop button to Stopped (red). In an emergency, turn off the main power switch to immediately stop all generator functions.
Trending Graphs
The Graph button on the Home screen displays historical trending data for sensors installed on the generator. All units include a nitrogen storage pressure transducer, so tank pressure is always trended. Additional optional graphs may include oxygen purity, air flow, nitrogen flow, and incoming air pressure, depending on unit configuration.
To adjust the Y-axis scale, press the min or max value boxes in the lower left corner of the graph screen, enter the desired values on the numeric keypad, and press Enter. The graph auto-adjusts. Use the M button to scroll through history and the G button to toggle horizontal grid lines. Press Next to advance to the next sensor graph, or Exit to return to the Home screen.
Menu Screen (Password Protected)
Press the Menu button on the Home screen to access the Main Menu. Entry requires the user password found on the second page of the hard-copy O&M manual included with your unit. The Menu provides access to Sensor Setup/Calibration, Alarms/Filter Parameters, Pressure Cut-In/Cut-Out Setup, Maintenance Menu, Information Screen, Logging (if equipped), Communication Settings (if equipped), and Pressure Settings (which also contains Duplex and Staging options if equipped). Factory Settings are reserved for South-Tek Systems technicians.
Sensor Setup / Calibration
Navigate to Menu → Sensor Setup/Calibration to calibrate sensors installed with the generator. All sensors use a 2-point linear calibration. Two known reference points — ideally at opposite ends of the sensor's measurement range — are required.
To perform a calibration, apply the first known reference value to the sensor, read the Current Raw value displayed on screen, and enter it in the Low Limit Raw field alongside the known value. Then apply the second reference and repeat for the High Limit Raw field. The controller uses these two points to calculate a linear correction.
| Sensor | Recommended Low Point | Recommended High Point |
|---|---|---|
| Pressure | 0–5 PSIG | 100–150 PSIG |
| O2 % (galvanic cell) | 0.5–1.5% O2 (certified gas) | 10–21% O2 (clean dry air) |
| O2 PPM (zirconium oxide) | 100 PPM | 1000 PPM |
Alarms / Filter Parameters
Navigate to Menu → Alarms/Filter Parameters to configure alarm setpoints and review filter status.
Alarm Setpoints — The O2 High Level alarm triggers when the current oxygen reading exceeds the setpoint. The Low N2 Tank Pressure alarm triggers when the tank pressure falls below the setpoint. Both alarms can be toggled on or off. The local audible buzzer can also be toggled on or off from the Other Settings screen within this menu.
Alarm Status & History — Press the red Alarm button (bottom right of any screen) to open the Alarm Status screen, which shows the current state of all alarms. From here, navigate to Alarm Details (list of active alarms with time/date stamps), Alarm History (scrollable log of up to 256 past alarms with duration records), or Clear History (requires entry of 1111 to confirm).
Filter Information — The Filter Info screen shows each filter's status as either Good or Overdue. When Overdue is highlighted, replace the corresponding filter as soon as possible. After replacing a filter, press the corresponding green filter element button on this screen to reset that filter's calendar. The FRP Freq screen shows the factory-recommended replacement schedule and current status of each element. The Filter History screen shows the last change date for each element, with the option to manually enter a date if the reset was performed earlier.
Pressure Cut-In / Cut-Out Setup
Navigate to Menu → Pressure Settings → Cut-In/Cut-Out Parameters to view the factory-configured pressure setpoints. The cut-out pressure is the tank pressure at which the generator enters Standby; the cut-in pressure is when it restarts.
Maintenance Menu
Navigate to Menu → Maintenance Menu to individually toggle each valve on the generator for diagnostic verification. Confirm valves are actuating correctly before and after a service event.
Before using this menu, set the generator to Stopped and close the nitrogen outlet valve from the storage tank. After completing valve testing, reset all valves to Off before restarting the system.
Information Screen
Navigate to Menu → Information to view the unit's serial number, software version, manufacture build date, commission date, and current total run hours. A shortcut to the Filter History screen is also available here.
Troubleshooting Quick Reference
| Symptom | Likely Cause | Action |
|---|---|---|
| Generator not cycling | Start/Stop button in Stopped state (red) | Press Start/Stop until it turns green |
| Generator not cycling | Low voltage / tripped breaker / blown fuse | Check electrical source; reset breaker; replace fuse on electrical panel |
| Generator not cycling | Low supply air pressure (CPx-Plus) | Check external compressor and internal pressure regulator |
| Running continuously / never reaches Standby | Cut-out pressure set incorrectly; wiring fault to pressure transducer; N2 leak | Verify cut-out setting matches factory spec; check transducer wiring; perform leak check throughout system |
| Low N2 purity | Product flow too high; O2 analyzer fault; O2 exhaust port blocked | Reduce product flow; check analyzer connections; verify exhaust tube is clear |
| No tank pressure building | Valve fault; wiring issue; disconnected pneumatic line; no pilot pressure | Use Maintenance Menu to toggle individual valves; check all pneumatic lines and wiring |
| Filter alarm active | Replacement interval reached | Replace filters; reset via Alarms → Filter Info on touchscreen |
Optional Feature: Data Logging
If the unit was ordered with the Data Logging option, navigate to Menu → Logging. The data table displays current, average, maximum, and minimum values for all installed sensors once logging is started.
To start logging to the on-screen table, press Press to Start Data Analysis. Press Press to Stop Data Analysis to pause. Press Reset Stats then restart to begin a fresh log.
To log data to a micro SD card (CSV format, compatible with Microsoft Excel):
- Confirm the screen shows SD Card: OK in the lower right corner.
- Press Reset Stats, then Press to Log to Excel.
- Press Press to Start Data Analysis to begin recording.
- To stop and retrieve data: press Press to Stop Excel Logging, then press Remove SD and wait for the green Ready message before physically removing the card.
- Insert the SD card into a PC. Navigate to: Excel > Excel 1 > [file number shown on logging screen]. Open the Logging Header Template in the same folder and copy the column headers into the data file before saving as an Excel document.
Optional Feature: Ethernet / Modbus TCP Communications
If the unit was ordered with the Ethernet option, navigate to Menu → Communication Settings to configure the network connection. A static IP address must be assigned to and entered into the controller. Subnet and gateway are not required for intranet access. Press the Connect button or cycle power after entering the IP address to establish the connection.
Three communication modes are available over Ethernet:
- Remote Access — Provides full touchscreen control from a Windows PC (Windows 7 or higher) using the Remote Access software included on the micro SD card. Connect via TCP/IP (Call) using the PLC's static IP. Load the PLC Image File (.urc) from the SD card to display the controller interface on screen.
- SD Card Access — Allows access to SD card files over the network without physically removing the card, using the SD Card Explorer software included on the micro SD card.
- Modbus TCP/IP — Enables integration with a BMS or SCADA system. Settings: Protocol TCP, Local Port 502, PLC configured as Slave. Refer to the Modbus addressing table in the O&M manual for register addresses.
Optional Feature: Duplex Operation
Duplex links the PLCs of two CPi-Plus & CPx-Plus generators to operate as a coordinated pair, meeting higher nitrogen demand than a single unit. One unit is designated Primary and the other Secondary, with automatic switching at a configurable interval to equalize run hours. Duplex is available only on units ordered with this option — contact South-Tek Systems to add it to a unit after purchase.
To configure Duplex, navigate to Menu → Pressure Settings → Duplex on one of the two units and press Press to Set Primary. Key settings:
| Setting | Factory Default | Description |
|---|---|---|
| Pressure Differential | 3 PSI | Offset between Primary and Secondary cut-in/cut-out pressures to prevent simultaneous cycling |
| Switch-Over Hours | 1,000 hours | Run hours before Primary and Secondary roles swap; user-adjustable on site |
Duplex requires 4 inter-unit wires. Refer to the Duplex wiring diagram in the O&M manual for terminal block assignments. Use the Test button to verify wiring during commissioning — Test mode accelerates the switchover timer to 5-second intervals for quick confirmation.
Optional Feature: Staging
Staging creates a redundant nitrogen generation system from two CPi-Plus & CPx-Plus units. One unit operates as Primary while the other remains on standby. After a configurable number of run hours, the units switch roles automatically. Unlike Duplex (where both units contribute to a shared flow), Staging is a true redundancy configuration — only one unit runs at a time. Staging is available only on units ordered with this option.
Navigate to Menu → Pressure Settings → Staging to configure. The Switch-Over Hours setpoint (default 1,000 hours) is user-adjustable. Staging also requires inter-unit wiring — refer to the Staging wiring diagram in the O&M manual for terminal block assignments.
Contact South-Tek Systems
Phone: (910) 415-1880
Email / Ticket: support@southteksystems911.zendesk.com