The integration of Internet of Things (IoT) infrastructures with Distributed Ledger Technologies (DLT) remains challenging due to the reliance on complex, tightly coupled back-end systems or centralized oracle services that hinder scalability, maintainability, and trust. This paper introduces a lightweight middleware architecture based on a Low-Code Development Platform (LCDP) that enables flexible and secure IoT-to-blockchain orchestration. We develop a custom workflow extension for the n8n platform that supports direct interaction with smart contracts, thereby removing the need for third-party oracle intermediaries. The proposed system was evaluated in a real-world deployment involving a network of Netatmo environmental sensors and the Alastria consortium blockchain. Experimental results show that the middleware can process 12 concurrent sensor data streams with an average end-to-end latency of 37.4 s, a delay dominated by the blockchain consensus time rather than middleware overhead, while ensuring the generation of immutable and verifiable audit trails. These findings demonstrate that low-code orchestration can deliver an effective, scalable, and fault-tolerant alternative for integrating IoT infrastructures with blockchain in Industry 4.0 environments.