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To integrate IMT’s Si-RS485 series sensors with your Victron GX device, follow these guidelines:
- Verify Sensor Compatibility: Ensure that the IMT solar irradiance sensor model you have is compatible with your Victron GX device.
- Connect Additional Sensors: If you have optional external module temperature, ambient temperature, or wind speed sensors, connect them to the solar irradiance sensor. They either plug directly into it or are pre-wired.
- Data Transmission: Once connected, the solar irradiance sensor will send all measurement data, including readings from any connected external sensors, to your Victron GX device using a single interface cable.
- Consider Sensor Capabilities: Different models within the Si-RS485 series have varying capacities for connecting external sensors. Some come with external sensors pre-wired. Choose a model based on your current and future monitoring needs.
- Direct Connection Options: For independent monitoring, you can connect the IMT Tm-RS485-MB module temperature sensor or IMT Ta-ext-RS485-MB ambient temperature sensor directly to the GX device, with or without the solar irradiance sensor.
Now you should be able to monitor solar irradiance, temperature, and wind speed data directly on your Victron GX device for a comprehensive understanding of your solar system’s environment.
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The IMT Si-RS485 series solar irradiance sensors utilize an RS485 electrical interface and communicate via the Modbus RTU protocol.
It’s essential for the Victron GX device to operate on version 2.40 or higher.
The IMT sensor should have at least firmware version 1.52; for additional details, please reach out to IMT.
Connection to the Victron GX device is established through a USB port, necessitating a Victron RS485 to USB interface cable.
An external DC power source ranging from 12 to 28 VDC is mandatory – note that the sensor does not draw power through the USB.
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Preparing the Power Supply:
- For 24V and 48V battery systems, incorporate a Victron DC-DC converter into the setup. Select the converter based on your system voltage (24/12, 24/24, 48/12, or 48/24).
- For a 12V battery system, you can power the sensor directly from the battery. Ensure the voltage remains above 10.5V at the sensor, taking into account any potential voltage drop in the cabling.
Wiring and Cabling:
- All extension cabling should comply with the minimum cross-sectional area requirements based on the DC supply voltage and cable length.
- Use shielded cabling with twisted pair cores to maintain signal integrity.
- If the installation exceeds 10m or there are potential interference issues, utilize high-quality cabling throughout, not just for the extension portion.
- Ensure cabling is routed separately from main DC or AC power cabling to avoid interference.
- Terminate all wiring securely and provide proper insulation from environmental factors.
- Keep the sensor housing sealed and intact to preserve warranty conditions.
Connecting the Sensor:
Connect the sensor’s data wires to the corresponding terminals in the terminal block:
- Brown wire (RS485 Data +) to the Orange terminal.
- Orange wire (RS485 Data -) to the Yellow terminal.
The power wires from the sensor are connected to the Victron DC-DC converter:
- Red wire to the positive terminal.
- Black wire to the negative terminal.
- Connect the shield (Black thick wire) to the ground or cable shield terminal (PE).
Configuring the Interface: Connect the terminal block to the Victron RS485 to USB interface, ensuring that:
- RS485 Data + terminal is connected to the RS485 Data A + on the interface.
- RS485 Data – terminal is connected to the RS485 Data B – on the interface.
For installations requiring an isolated interface, use the Hjelmslund USB485-STIXL model.
Final Steps:
- Connect the Victron RS485 to USB interface to the Victron GX device via the USB port.
- Perform a system check to confirm that the sensor operates correctly and that readings are consistent.
- Document the installation details, including component serial numbers, for warranty and support.
Post-Installation Checklist:
- Confirm all connections are secure and correctly polarized.
- Insulate and weatherproof all outdoor wiring.
- Label components and wiring for easy identification.
- Provide the site manager with a summary of the installation for future maintenance.
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The IMT Si-RS485 series solar irradiance sensors are designed to operate safely with a maximum DC power supply voltage of 28.0VDC. For systems with 24V and 48V battery banks, it’s necessary to incorporate a suitable Victron DC-DC converter (24/12, 24/24, 48/12, or 48/24) or an AC-DC adapter for compatibility.
In cases of 12V battery banks, the IMT Si-RS485 series can be directly connected to the battery, functioning efficiently down to a minimum voltage of 10.5V. Bear in mind the potential for voltage drop in the cables and plan accordingly.
For intricate installation procedures and technical specifics, please consult the IMT Si-RS485 series ‘Quick Reference Guide’ and the Victron RS485 to USB interface cable ‘Datasheet’.
To maintain optimal performance and signal quality, ensure that:
- The extension cables meet the minimum cross-sectional area requirements as per the given guidelines, which vary based on DC supply voltage and cable length.
- The extension cables are adequately shielded with twisted pair cores.
- In installations where total cable length exceeds 10m or where specific interference issues are present, shorten the original cable attached to the Victron RS485 to USB interface to no more than 20cm, using high-quality cabling for the entire length.
- Install cabling away from primary DC or AC power lines.
- All wires, including unused ones, are securely terminated and shielded from environmental elements.
- Avoid opening or tampering with the sensor housing during installation to maintain its sealing integrity and warranty.
The IMT Si-RS485TC series sensors come with internal Galvanic Isolation (up to 1000V) between the power supply and RS485 Modbus circuits, making the non-isolated Victron RS485 to USB interface suitable for most setups.
If an isolated RS485 to USB interface is preferred, the Hjelmslund Electronics USB485-STIXL is the only compatible option for the GX device.
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