We have previously explored various industrial Raspberry Pi systems and gateways with built-in RS-485, but have yet to cover a dedicated RS-485 Raspberry Pi HAT. Filling this gap, EngineElectronicAccessories, a Swedish developer, has introduced the “Industrial RS485 / Modbus HAT” for industrial automation, monitoring, and the OpenPLC open-source PLC suite.
This board features an onboard RS-485 transceiver with TVS diode protection, enabling long-distance communication via the RS-485 standard. It utilizes the Pi’s hardware UART interface and incorporates Tx/Rx LEDs for diagnostics. Additionally, the board accepts a 7V to 32V DC input, allowing both the HAT and the Raspberry Pi to be powered directly from a standard 24V rail, removing the need for a separate USB power supply in a control cabinet.
Industrial RS-485/ Modbus HAT specifications:
– Compatibility: All Raspberry Pi boards with a 40-pin GPIO header (Pi 3, Pi 4, Pi 5, Pi Zero, etc.)
– Host interface: UART (/dev/ttyAMA0 or /dev/ttyS0) via 40-pin GPIO header
– Communication:
– 5-pin heavy-duty screw terminals with RS-485 A, B, and GND signals (plus power signals)
– Off-the-shelf RS485 to TTL module
– Misc:
– Onboard Tx and Rx diagnostic LEDs
– Built-in TVS diodes for ESD and voltage spike protection
– Power:
– Input Voltage: 7V to 32V DC via screw terminals (supports standard 12V and 24V industrial rails)
– Integrated DC-DC buck converter (Mini560 DC 5V 5A step-down module)
– Provides 5V DC to power both the Raspberry Pi and the RS-485 transceiver
– Dimensions: Compact HAT form factor (compatible with most DIN-rail and standard Pi enclosures).
The board is “OpenPLC Optimized,” with pinout and timing configured for low-latency ladder-logic execution, making it very useful for energy-monitoring projects such as reading SDM smart meters or interfacing with solar/battery systems. The project is partially open source, and PDF schematics and documentation are available on GitHub (note that the RS-485 interface is not galvanically isolated, which is common in this price range).
The Industrial RS485 / Modbus HAT is available on Tindie for $9, shipping from Sweden with costs ranging from $7.4 to $15, contingent on the destination country. Although we had not previously written about RS-485 HATs for Raspberry Pi SBCs, many other models are available on AliExpress and Amazon.