Nexus Gateway

Australian Energy Research Laboratories (AERL) was founded in 1985 by Stuart Watkinson to commercialise the Power Optimizer, which he developed while studying at the University of Queensland. It became the AERL MAXIMIZER™, a universal maximum power point tracker (MPPT).

Today AERL designs, integrates and supports power conversion, lithium energy storage, monitoring and earth-fault detection products for commercial, industrial and off-grid energy systems, including oil and gas, mining and telecommunications sites.

Trademark

AERL and the AERL logo are trademarks owned by AERL Holdings Pty Ltd and used by AERL Pty Ltd under licence. These trademarks may be registered in Australia and other countries. Selectronic, SP PRO, SP LINK, Pylontech, Deye and other third-party names are trademarks of their respective owners; they are used here only to identify compatible equipment.

Effective Date

November 2026 (11/2026)

Notice of Copyright

AERL Nexus Gateway User Manual © 2026 AERL Pty Ltd. All rights reserved.

Disclaimer

UNLESS SPECIFICALLY AGREED TO IN WRITING, AERL PTY LTD:

(a) MAKES NO WARRANTY AS TO THE ACCURACY, SUFFICIENCY OR SUITABILITY OF ANY TECHNICAL OR OTHER INFORMATION PROVIDED IN ITS MANUALS OR OTHER DOCUMENTATION.

(b) ASSUMES NO RESPONSIBILITY OR LIABILITY FOR LOSS OR DAMAGE, WHETHER DIRECT, INDIRECT, CONSEQUENTIAL, OR INCIDENTAL, WHICH MIGHT ARISE OUT OF THE USE OF SUCH INFORMATION.

THE USE OF ANY SUCH INFORMATION WILL BE ENTIRELY AT THE USER'S RISK.

Contact Information

Australian Energy Research Laboratories, 1/75 Bluestone Circuit, Seventeen Mile Rocks QLD 4073, Australia

aerl.com.au · [email protected] · [email protected] · 1800 950 865

This manual contains important safety information and installation instructions for the AERL Nexus Gateway: the Nexus Lite and the Nexus 4G. It uses the following symbols for important operating information and potentially dangerous conditions.

Important

Indicates information that must be followed to ensure proper operation of the Nexus.

Caution

Indicates a critical procedure for the safe installation of the unit, or safety information that must be followed.

1.1About This Manual

This manual gives installation and operating instructions for the Nexus Lite and the Nexus 4G. Everything in it applies to both models except the Nexus 4G chapter, which covers what only the Nexus 4G has. Read all of its instructions and cautions before you start the installation.

Only qualified electricians and technicians may install the Nexus.

Do not disassemble or attempt to repair this product unless you are qualified and have written permission from AERL to do so.

AERL will not be held responsible in any way for mishandling of this product or for installation of the product in a manner that does not comply with the instructions in this manual.

1.2Safety Notes

Caution

• The Nexus is designed for indoor installation only. Do not mount it where splashing water or direct sunlight can reach the unit.
• The DC power input is galvanically isolated, but always install and service the unit with the upstream supply isolated.
• Use a 5 V USB-C supply, or a DC source within the 12–60 Vdc input range. Applying voltages outside the rated range may damage the unit and will void the warranty.

The AERL Nexus Gateway is a communications gateway for remote monitoring, configuration and control of distributed energy systems. It connects field equipment (solar charge controllers, batteries, inverters and other compatible CAN bus and Modbus devices) to AERL Cloud, where data can be viewed, alerts set up and equipment managed from anywhere.

Its main features are:

• AERL Cloud compatible out of the box: no configuration on the device for an Ethernet connection.
• Isolated CAN bus and RS485 ports for safe interfacing with field equipment.
• Wide-input DC power (12–60 Vdc), or 5 V USB-C power for bench use.
• Dual-band Wi-Fi and Ethernet.
• Compact enclosure for wall or DIN-rail mounting.

2.1Models

2.2What You Will Need

• An AERL Nexus Gateway.
• A power source: a 12–60 Vdc supply (permanent installation) or a 5 V USB-C supply (bench or commissioning).
• An Ethernet cable to a network with internet access; or, for the Nexus 4G, a SIM card with a data plan (see the Nexus 4G chapter).
• CAT5e or CAT6 patch leads for the CAN and RS485 equipment you will monitor.
• An AERL Cloud account. Sign up at aerl.cloud/signup if you do not already have one.

The serial number and pin code printed on the Nexus label are needed to claim the Nexus in AERL Cloud. Keep the label accessible during commissioning.

The complete specifications are in the Nexus Gateway datasheets (Nexus Lite and Nexus 4G).

3.1General and Power

3.2Connectivity

4.1Location

Caution

• The Nexus enclosure is rated IP20 and is intended for indoor installation only. Do not mount it where splashing water, direct sunlight or excessive dust can reach the unit.
• Route cables downwards away from the Nexus, so that any moisture that condenses on the cables does not run back into the product.
• Allow at least 25 mm of free space on all sides of the enclosure for airflow.

In a system with an RS485 (Modbus) device such as a Selectronic SP PRO, mount the Nexus as close as possible to that device, so that the RS485 run is short.

4.2Mounting

Mount the Nexus on a wall, using the mounting flanges, or on a 35 mm DIN rail. Mount it with the connectors facing downwards or sideways, so that cables leave the connectors without strain.

4.3Connectors

The Nexus 4G also has an LTE antenna connector, a SIM card slot, HDMI, RST and an RLY / IO terminal: see the Nexus 4G chapter.

4.4DC Power Input

The Nexus can be powered from either of two inputs: use only one at a time. Use the DC input for a permanent installation. Connect a DC supply between 12 V and 60 V to the DC IN terminal. The input is galvanically isolated from the rest of the Nexus.

1. Isolate the supply.
2. When the Nexus is fed from a battery, fit a fuse or circuit breaker in its supply, close to the battery.
3. Wire the plug with the supply off, checking the polarity: positive to pin 1 (+), negative to pin 2 (−).
4. Push the plug into the DC IN socket and restore the supply.

Important

The input is protected against reverse polarity, but confirm the polarity before you apply power. Prolonged incorrect connection may damage the input stage.

4.5USB-C Power

For bench or commissioning use, connect a 5 V USB-C supply to the USB port. The USB-C port is a power input only: it is not a data connection.

4.6Power-On

The Nexus starts automatically when power is applied. It then:

1. Starts its local services.
2. Connects to the network.
3. Connects to AERL Cloud.
4. Starts finding the connected field equipment.

The Nexus has two CAN bus sockets and one RS485 Modbus socket, all RJ45. Use CAT5e or CAT6 patch leads, shielded for CAN runs, and keep data cables away from DC power cables.

5.1CAN Bus

The CAN interface runs at a fixed 500 kbps, matching the AERL device family. Every device on the bus must use 500 kbps.

All pins not listed are not connected.

• The CAN interface is galvanically isolated.
• CAN 1 and CAN 2 are linked inside the Nexus (one CAN interface, two sockets), so the Nexus can sit inline on the bus: for example, battery to CAN 1, and CAN 2 on to the inverter or MPPT.
• The Nexus has no built-in termination. A CAN bus is terminated with 120 Ω at both ends. If the Nexus is at an end of the bus, fit a 120 Ω RJ45 termination plug in its unused CAN socket. If it is mid-bus, fit no plug.

5.2RS485 Modbus

The RS485 port connects a Modbus RTU device, such as a Selectronic SP PRO inverter. The Nexus is the Modbus master: do not put another Modbus master on the same link.

All other pins are not connected. The RS485 port is galvanically isolated. Follow the device manufacturer's wiring guidance, and terminate the bus correctly at both ends.

Two LEDs next to the RS485 socket, Tx and Rx, show the link working: Tx flickers when the Nexus sends a Modbus request, Rx when the device replies.

5.3Supported Equipment

CAN devices are found automatically. A Modbus device is added to the Nexus in AERL Cloud (see the AERL Cloud chapter); AERL Cloud allows one Modbus device per gateway.

The current list of supported equipment is on the AERL Cloud help site, docs.aerl.cloud (Devices).

5.4CoolMax SRX and SRX-R

Connect a Nexus CAN socket to a CANBUS RJ45 socket on the CoolMax SRX (inside the access cover) or on the SRX-R backplane, with a straight-through patch lead. Run the bus on through the other SRX units from their second CANBUS socket. Enable the 120 Ω termination switch on the last SRX on the bus only. Leave the SRX CAN bus speed at its default, 500 kbps.

5.5LiFe² 5120S Battery

Connect the Nexus inline on the battery's CAN bus: the master battery's COMM port to Nexus CAN 1, and Nexus CAN 2 on to the inverter or MPPT. The master battery's COMM port has an internal 120 Ω termination, so the battery is one end of the bus. If the Nexus is the other end, fit a 120 Ω termination plug in its spare CAN socket. The LiFe² AERL Cloud Integration Guide has the details.

5.6Kakadu 120 Battery

The Kakadu 120 needs a Nexus Gateway to manage its communications. Connect the INV port of the master BMS to a Nexus CAN socket. The Master Unit setting on that BMS sets its terminating resistor; on every other BMS it is off. For a Kakadu system with Selectronic SP PRO inverters, follow the Kakadu 120 commissioning guide for the SP PRO SPLC1202 and CoolMax SRX.

5.7Selectronic SP PRO

Connect a straight-through CAT5e or CAT6 patch lead from Port 1 on the SP PRO's comms card to the Nexus RS485 socket. In SP LINK, switch Modbus on with Modbus address 1, 9600 baud, 8 data bits, no parity, 1 stop bit, then add the SP PRO to the Nexus in AERL Cloud. On a PowerChain system, connect to the PowerChain master. The Nexus Gateway SP PRO Setup Guide has the full procedure.

5.8Battery Sense

The Battery Sense connects to a CANBUS socket on a CoolMax SRX, as its manual describes. When the Nexus is on the same CAN bus, the Battery Sense readings appear in AERL Cloud. If the Battery Sense is the last device on the bus, set its 120 Ω termination switch to ON.

5.9AERL Industrial HMI (HMI-10)

The HMI-10 has the Nexus software built in: it does not connect to a Nexus Gateway. See the AERL Industrial HMI (HMI-10) User Manual.

The Nexus needs internet access to send its data to AERL Cloud.

6.1Ethernet

Connect a Cat5e or better Ethernet cable from the site router or switch to the ETH port. The Nexus gets its address by DHCP and connects to AERL Cloud on its own: no further configuration is needed. The cable can be plugged in before or after power-on. Ethernet is recommended for permanent installations.

6.2Wi-Fi

The Nexus has dual-band Wi-Fi. Wi-Fi is not set up from AERL Cloud: if Ethernet is not available at the site, contact AERL for help with a Wi-Fi set-up. Have the Nexus serial number and the site's Wi-Fi network name ready.

6.3Firewall Requirements

The Nexus starts every connection itself: no inbound ports need to be opened. The network must allow outbound HTTPS (TCP port 443) to AERL Cloud services (aerl.cloud), and network time (NTP). If the site's network filters outbound traffic, contact AERL support for the list of addresses to allow.

6.4How Often Data Is Sent

The Nexus detects the type of connection it has. It sends data every minute on Ethernet or Wi-Fi, and every ten minutes on a cellular connection (Nexus 4G). During a network outage it stores data locally and uploads it automatically once it reconnects.

Once the Nexus is powered, online and wired to the field equipment, claim it in your AERL Cloud organisation. Its data is visible only after it is claimed.

7.1Claiming the Nexus

You need the Owner, Admin or Technician role in the organisation to claim a gateway.

1. Sign in at aerl.cloud. If you have no account, create one at aerl.cloud/signup; your first sign-in asks you to create an organisation.
2. Click Add Gateway on the dashboard or the Gateways page, or the + button in the top bar.
3. On Claim Your Gateway, enter the Serial Number and Pin Code printed on the Nexus label, then click Claim Gateway.
4. On Gateway Claimed!, choose Assign to Existing Location, or Create New Location with the site's name and address. Click Continue.
5. On Setup Complete!, click View Location.

There is nothing to configure on the Nexus itself: it connects to AERL Cloud with credentials set at manufacture. If a gateway has been claimed by the wrong organisation by mistake, contact AERL support.

7.2Confirming the Equipment

• CAN devices are found automatically and appear under the location once the Nexus is online.
• A Modbus device (for example an SP PRO) is added in AERL Cloud by a user with the Owner or Admin role: open Gateways and click Manage beside the Nexus. In Edit Gateway, under Modbus Devices, click Add Device, choose the Device Product, then click Add Device. The Nexus loads the new configuration within about five minutes, without a restart.

7.3Giving Others Access

To give a customer or colleague access, invite them from the organisation's Invitations page in AERL Cloud and choose their role.

7.4Further Reading

The AERL Cloud help site, docs.aerl.cloud, covers organisations, locations, users, alerts and reports:

• Quickstart: docs.aerl.cloud/start/quickstart
• Gateways: docs.aerl.cloud/cloud/gateways
• Gateway configuration: docs.aerl.cloud/cloud/gateway-configuration
• Devices: docs.aerl.cloud/cloud/devices
• Alerts and events: docs.aerl.cloud/cloud/alerting-and-events/overview

The Nexus 4G is the Nexus Gateway with an integrated 4G cellular modem, digital inputs and output relays. Everything else in this manual applies to it unchanged.

8.1SIM Card

The Nexus 4G takes a Micro-SIM in the SIM slot. Use a SIM with a data plan that covers the site.

1. Isolate the power to the Nexus 4G.
2. Push the Micro-SIM into the SIM slot until it latches. To remove it, push it in again and release.
3. Restore the power.

Important

Contact AERL before you commission a Nexus 4G on cellular: AERL confirms the SIM and the network settings it needs.

8.2Antenna

Connect the LTE antenna to the LTE connector, and place the antenna where the cellular signal is best, outside any metal enclosure.

8.3Cellular Data

On a cellular connection the Nexus 4G sends its data every ten minutes, to keep the data used low. AERL Cloud shows the Nexus 4G online once it has reported in the last 15 minutes, as for any gateway.

8.4Digital Inputs and Output Relays

The RLY / IO terminal carries two output relays (R1, R2) and four digital inputs. The relays are for SELV circuits only: 30 V DC or 24 V AC at most, 3 A.

Caution

Contact AERL before you wire the RLY / IO terminal. Never connect mains voltage to the relays or the inputs.

9.1Normal Operation

Once claimed and connected, the Nexus works on its own. It:

• Reads the connected field equipment continuously.
• Stores data locally during a network outage and uploads it once the connection returns.
• Renews its AERL Cloud credentials automatically.
• Applies software updates published by AERL.

No interaction with the Nexus itself is needed. All monitoring and configuration is done in AERL Cloud.

9.2Software Updates

The Nexus updates itself automatically while it is connected to AERL Cloud: no installer action is needed. Updates are installed at a quiet time; the Nexus restarts to finish an update and is offline for a short time. If an update does not work, the Nexus goes back to the previous version by itself.

Firmware updates for connected AERL equipment, such as CoolMax SRX controllers, are started from AERL Cloud: see the AERL Cloud help site.

9.3Status in AERL Cloud

The Nexus is monitored from AERL Cloud. On the Gateways page each gateway shows its Status and Last Seen time; its Manage window shows its Hub ID and software (Firmware) version.

• Online: the Nexus has reported in the last 15 minutes.
• Offline: it has not reported in the last 15 minutes, or has never reported.

Equipment on a gateway shows Online, Sleeping (normal for a CoolMax SRX that is quiet overnight), Offline or Inactive.

9.4Troubleshooting

For alarm codes and faults of the connected equipment, see the AERL Cloud help site, docs.aerl.cloud/troubleshooting.

If these checks do not solve the problem, contact AERL support on 1800 950 865 or at [email protected]. Have the Nexus serial number (or Hub ID) and the time it went offline ready.

10.1Compliance

The AERL Nexus is designed and tested to applicable Australian electrical and electromagnetic compatibility standards for Class B information-technology equipment installed indoors. Refer to the markings on the unit and the accompanying declaration of conformity for the standards covered by your unit's revision.

10.2Warranty

The Nexus Lite and the Nexus 4G have a 2-year warranty. It starts 30 days after AERL dispatches the Nexus, or on the day it first connects to AERL Cloud if that is sooner.

Register your Nexus at aerl.com.au/warranty-registration. Registration does not change the 2-year warranty.

Our goods come with guarantees that cannot be excluded under the Australian Consumer Law. You are entitled to a replacement or refund for a major failure and compensation for any other reasonably foreseeable loss or damage. You are also entitled to have the goods repaired or replaced if the goods fail to be of acceptable quality and the failure does not amount to a major failure.

The full terms and the claim procedure are in the AERL Nexus Gateways Warranty Statement, at aerl.com.au.

Record the details from your Nexus label here:

10.3Change Log