STAHL ET-75 HMI Display Module Operator Interface ET-75-RS422

STAHL ET-75 HMI Display Module Operator Interface ET-75-RS422

The R. STAHL ET-75 (Model: ET-75-RS422) is an intrinsically safe Human-Machine Interface (HMI) terminal engineered for demanding visualization, process monitoring, and control tasks in hazardous marine and industrial environments. Part of the Falcon series (Exicom platform), the ET-75 is certified for direct installation in ATEX/IECEx Zone 1, 2, 21, and 22 as well as Class I, Division 1 & 2 hazardous locations without requiring heavy explosion-proof (Ex d) flameproof enclosures.

Featuring an industrial-grade backlit graphic display, a chemical-resistant front membrane keypad, and an isolated RS-422 serial communications bus, the ET-75-RS422 interfaces seamlessly with legacy and modern marine automation systems, ballast control systems, tanker cargo monitoring consoles, drilling packages, and central DCS/PLC networks.

Model Details

• Manufacturer: R. STAHL HMI Systems GmbH
• Product Series: Falcon / Exicom Series
• Type Code: ET-75-RS422
• Hardware Article Number (HW): 200020620200
• Software Article Number (SW): 200120400600
• Compatible Variant References: ET-75-B-RS422, ET-75-B-PACK

Key Features

1. Zone 1 / Div 1 Direct Field Mounting: Certified Ex ia IIC/IIB intrinsically safe architecture eliminates the need for bulky purging systems or heavy flameproof enclosures at the operator station.
2. High-Noise-Immunity RS-422 Bus: Point-to-point and multi-drop fieldbus communication across long cable runs in high-EMI marine engine rooms and switchboard compartments.
3. Rugged Front Panel Protection: Rated up to IP65 front protection with UV-stable, chemical-resistant polyester foil membrane for resistance against offshore salt spray, oils, and cleaning agents.
4. Flexible Digital I/O Expansion: Integrated terminals for up to 8 external floating contacts/switches (3.3 V, 2 mA) and external barcode/proximity reader interface connections.

System Compatibility & Drop-In Replacement

• Replaces Legacy Units: Direct functional replacement for legacy STAHL ET-4A, ET-6, and ET-9752 operator interfaces that have retired ATEX compliance standards.
• Isolators & Barrier Modules: Fully compatible with R. STAHL ISPAC 9185/11 fieldbus isolating repeaters, 9143 series power supplies, and 9721 series network links.
• Supported Controller Protocols: Siemens SIMATIC S7 / S5 (via 3964R / RK512), Modbus RTU / ASCII (Master/Slave), Allen-Bradley DF1, ABB, and Schneider Modicon architectures.

Applications

• Marine Offshore & Tankers: Inert Gas Systems (IGS), Ballast Water Treatment Systems (BWTS), Tank Gauging & Level Monitoring consoles, and Purifier Room control panels.
• Drilling Rigs & FPSO Modules: Mud logging monitoring, BOP control interfaces, top-drive instrumentation, and hazardous deck station displays.
• Chemical & Petrochemical Refineries: Local pump skid monitoring, gas compressor local displays, hazardous batching stations, and centrifuge operator consoles.
• Pharmaceutical & Cleanroom Suites: Reactor temperature display panels and solvent dispensing operator terminals.

Frequently Asked Questions

Can the STAHL ET-75-RS422 be installed directly in an Ex Zone 1 area without an explosion-proof housing?

Yes. The ET-75-RS422 is designed with intrinsic safety protection (Ex ia IIC/IIB). When powered through approved intrinsically safe barriers/isolators and wired according to ATEX/IECEx installation standards, it mounts directly onto standard control console front plates in Zone 1, 2, 21, and 22.

What is the primary difference between the ET-75-RS422 and the ET-75-A/B variants?

The ET-75-RS422 specifically features a dedicated, bus-compatible RS-422 differential serial interface designed for point-to-point or multi-drop communications to isolating repeaters (e.g., STAHL 9185/11) and PLCs. The “-B” and “-PACK” suffixes denote revision stages and bundled hardware accessories (mounting brackets and terminal blocks).

How do I back up or transfer configuration projects to the ET-75?

Configuration projects are loaded via the communication port using R. STAHL’s proprietary engineering software (such as SPS-Programmierkabel / Falcon transfer tools). Ensure the transmission protocol match (baud rate, parity, and station address) matches the host PLC driver before flashing runtime files.

What should I inspect if the ET-75 display illuminates but communication fails with the PLC?

First, verify that the TxD and RxD differential polarity (+/A and -/B) is not inverted on the terminal strip. Second, verify the signal isolation barrier in the safe-area cabinet is operational and transmitting pulses. Third, ensure the shield is grounded at one designated point to prevent ground loop noise from corrupting data frames.