Explore our premium grade HART-to-MODBUS converters, RS485 serial servers, and data integration interfaces engineered for mission-critical industrial architectures.
Bidirectional data mapping between Modbus RTU register sets and HART command layers. Ideal for system migration and hybrid network integration.
The SM100-HHE transmitter features integrated dynamic variable extraction, converting process automation signals to structured Modbus registries seamlessly.
Engineered for converting Modbus digital data streams back to precise multivariable analog 4-20mA current loops for legacy PLC control.
Compact design, cost-efficient, and optimized for integrating field smart transmitters directly to distributed control systems via standard RS485.
Bridges the gap between legacy serial communications and modern high-speed Industrial Ethernet network topologies with multi-port interfaces.
Integrates cellular telemetry networks for remote environmental and utility infrastructure monitoring, collecting dynamic modbus variables.
Multi-channel isolation and precision conversion parameters, specifically structured for robust oil refining and chemical processing lines.
Advanced protocol parsing chipset optimizes transmission speed, minimizing polling latency between master controllers and peripheral sensors.
Established in 2007, Jiaxing Songmao Electronics Co., Ltd. has developed into a leading high-tech enterprise specializing in the independent R&D, production, and worldwide sales of core industrial communication interfaces. Driven by persistent technological innovation, our engineered solutions focus heavily on HART protocol communications, Modbus integrations, and multivariable industrial data collectors.
Over the course of 18+ years, our technical teams have achieved breakthroughs in signal processing and magnetic isolation, establishing a position of deep domain authority. Headquartered in our 1,073 m² state-of-the-art office and laboratory space, our strict quality control metrics guarantee optimal reliability across harsh processing environments internationally.
Bridging legacy analog infrastructures with advanced Industrial Internet of Things (IIoT) communication topologies through high-fidelity hardware solutions.
Traditional process automation fields contain immense electrical noise, ground potential differentials, and transient surges. Our converters implement galvanic isolation barriers (exceeding 1.5KV AC) using state-of-the-art optoelectronic and magnetic coupling configurations. This guarantees signal fidelity when translating analog loop current (4-20mA) and overlaid Frequency Shift Keying (FSK) HART digital data into balanced differential RS485 Modbus registers, protecting host PLC systems from field-side damage.
HART-enabled field devices yield complex multi-variable parameters including Primary Variables (PV), Secondary Variables (SV), Tertiary Variables (TV), and Quaternary Variables (QV). Our proprietary microcode allows automated HART command execution (HART CMD 0, 3, 15, and 33) and populates dedicated holding and input Modbus registers dynamically. Industrial PLCs can thus query multivariable parameters using standard single-command Modbus RTU/TCP polling cycles, eliminating protocol parsing overhead.
Modern plants demand integration directly into enterprise cloud platforms. Our technological roadmap is expanding deeper into Modbus TCP/IP servers and cellular telemetry models like the SM626H-D. Operating over 4G/GPRS All-Netcom architectures, these units process raw edge data, package the Modbus records, and upload telemetry directly to off-site SCADA systems. This reduces remote site footprint requirements while offering robust diagnostics, event notifications, and historical buffering.
Songmao's high-reliability protocol converters are field-certified and deployed across diverse processing industries globally.
Sourcing process automation interfaces from Songmao’s state-of-the-art Chinese factory offers global distributors and systems integrators unmatched strategic advantages. Located within the heart of the Yangtze River Delta industrial hub (Jiaxing, Zhejiang), we tap into the world's most concentrated microelectronic component and precision raw material supply chains. This localized ecosystem allows us to achieve incredibly short production lead times and maintain agile design-to-delivery loops for custom OEM or ODM requirements.
Additionally, our 18+ years of dedicated quality control procedures utilize automated verification rigs, thermal environmental stress chambers, and electromagnetic compatibility (EMC) testing benches. By optimizing manufacturing workflows and raw material procurement channels, we combine highly competitive wholesale pricing structures with the top-tier component lifetimes needed for demanding industrial environments. Our manufacturing resilience keeps your integration projects insulated from component shortages and pricing shocks.
Process plants globally are transitioning from traditional isolated analog instrumentation loop designs (4-20mA current loop systems) to digital network topologies (Industrial Ethernet, RS485 modbus, and wireless edge systems). However, replacing entire sensor installations, cabling systems, and host PLC systems is economically impractical for brownfield sites. Protocol converters and transducers serve as the crucial middleware enabling cost-effective upgrades.
Songmao Electronics bridges the hardware gap across various international markets. From North American oil and gas processing plants requiring explosion-proof barrier protection to European district heating networks operating vast Modbus loops, our products are engineered to fit globally standardized din-rail profiles and electrical environments. We enable the step-by-step modernization of legacy infrastructure with zero operational downtime.
We validate our development models against strict industrial standards. Every product unit is calibrated to assure signal accuracy, electromagnetic immunity, and thermal stability in field operations.
Local Support & Integration Engineering: Our technical team assists field engineers globally, offering wiring schematics, configuration utilities, and Modbus register mapping support for fast deployment. Whether integrating with Siemens, Rockwell Automation, Honeywell, or Emerson DCS ecosystems, we provide remote assistance, documentation, and tailored firmware revisions to guarantee seamless operation.
Expand your process automation insights with our deep technical analysis of Modbus connectivity, HART polling procedures, and serial converter setups.
Jul 2026
MODBUS TCP (Transmission Control Protocol) is a widely used serial communication protocol in industrial systems. Discover our step-by-step setup guides mapping RS485 frames to TCP sockets.
Jul 2026
In industrial automation, intelligent instruments, PLC control systems, and IoT data collection, Modbus remains the foundational standard. Learn how standard registries organize variables.
Read detailed technical answers on how to select, deploy, and maintain your industrial communication converters.
Modbus RTU is a serial communication protocol that runs on RS485 or RS232 physical media, using binary coding and CRC error checking for reliable, long-distance bus topologies. Modbus TCP/IP packages the same application data frame inside a standard TCP/IP packet, running on Ethernet media. While Modbus RTU is highly cost-effective and suited for simple daisy-chained networks, Modbus TCP/IP allows for higher speeds, broader network distances, and integration with standard IT network infrastructure.
A HART to Modbus converter acts as a HART master device. It periodically sends digital HART commands (such as Command 3 or Command 33) to the connected field transmitters. The transmitters respond with digitized variables representing process parameters (temperature, pressure, etc.) and diagnostic data. The converter parses these responses and maps them to standard Modbus RTU holding registers (4xxxx) or input registers (3xxxx), allowing host PLCs to retrieve the data using a single Modbus read command.
RS485 networks often span long distances, running between different buildings or sections of a factory. This can result in ground potential differences between nodes. Without isolation, these differences cause ground loop currents that degrade signals and can damage equipment. Galvanic isolation (using optical or magnetic couplers) decouples the transceiver circuitry from the physical line, protecting your hardware against transient high-voltage surges and electromagnetic interference.
For proper digital HART signal modulation on a standard 4-20mA current loop, the total loop impedance must be between 230 and 1100 ohms. A minimum load resistance of 250 ohms is recommended. If the internal loop impedance of your power supply or receiver is too low, you must add a 250-ohm resistor in series with the loop. This ensures the modulated FSK signal has sufficient amplitude for the HART modem to detect and decode.
Yes, using HART multidrop mode. In a multidrop configuration, multiple transmitters (up to 15 or 64, depending on the HART version) are wired in parallel across the loop. In this setup, each device is assigned a unique polling address (1-63), and their analog loop currents are fixed at a minimum value (typically 4mA) to power the internal circuitry. Communication is handled digitally via HART commands. The converter polls each device address sequentially to gather process variables.
Wireless data collectors (such as the SM626H-D) aggregate local sensor data via RS485 Modbus or analog inputs, process the signals, and transmit the data using cellular networks (like 4G, GPRS, or LTE-M). The device establishes a secure connection to a remote server or cloud system, uploading data packets at configured intervals or when specific alarm thresholds are crossed. These modules often include local storage buffers to protect data against temporary network outages.
Browse our specialized product configurations designed for high-density, multi-channel data acquisition and isolated protocol translation.
Designed for heavy-duty industrial telemetry. Features robust RS485 shielding, supporting up to 8 independent HART channels.
A high-accuracy analog-to-digital data acquisition unit, designed to simplify multivariable processing and PLC bus configuration.
Available for volume wholesale orders, the SM100-B features reliable, proven operation on process automation networks worldwide.
A DIN-rail mounted digital-to-analog converter that maps Modbus registers to precise analog outputs for valve and actuator control.
High-density module designed to aggregate up to 16 HART-compliant transmitters on a single Modbus network node, saving cabinet space.
A high-performance gateway offering fast protocol conversion, rugged electrical protection, and easy setup via config software.
Equipped with dual serial interfaces, the SM101-B simplifies integration with legacy PCs, HMIs, and PLCs across diverse processing lines.
Features complete galvanic isolation to prevent ground loops. Ideal for long-distance industrial buses and harsh electrical environments.