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Modbus RTU

Remote Terminal Unit

Physical Layer: Uses serial connection RS-485

Architecture: Master/Slave (or Client/Server), where one master device polls multiple slave devices for data

Daisy-Chain Wiring: Devices connect in series on twisted-pair cables (A+ to A+, B- to B-) for up to 32 devices and 4,000 feet before repeaters

Error Checking: Uses Cyclic Redundancy Check (CRC) for reliable data integrity

Message Structure: Includes Slave ID, Function Code, Data, and CRC checksum

Product Description

Modbus RTU excels in applications needing robust, long-distance communication between many devices in harsh factory or plant settings, forming the backbone of many legacy and modern industrial networks, though Modbus TCP (Ethernet-based) is used for higher-speed, IP-based applications.

The Chiltrix heat pumps operate on MODBUS and make a connection available for external controls access. This is an RS485 connection that allows a customer-provided controller (based on Arduino, Raspberry Pi, or other) to monitor and control various aspects of operating the heat pump.

Modbus RTU excels in applications needing robust communication between devices in forming the backbone of many legacy and modern industrial networks. Modbus is native to the Chiltrix heat pump and is used for internal control.