Honeywell MIDAS-2MLQ Gas Detector for MIDAS

Honeywell MIDAS-2MLQ Gas Detector for MIDAS: Control System and Upstream–Downstream Coordination

In modern industrial automation, gas detection is not a standalone function — it is a deeply integrated layer within a multi-tier control architecture. The Honeywell MIDAS-2MLQ, identified by SKU 2MLQ-TR1C-CC, is a system-compatible gas detector module engineered specifically for deployment within the Honeywell MIDAS (Modular Industrial Detection and Alarm System) platform. Its value is best understood not in isolation, but in the context of how it coordinates with the control layer, I/O layer, network layer, power layer, human-machine interface layer, and field execution layer to deliver a coherent, scalable, and maintainable safety architecture.

The MIDAS-2MLQ is designed to slot directly into the MIDAS controller backbone, enabling seamless signal acquisition from electrochemical, catalytic bead, or infrared sensing cartridges. Within the control hierarchy, it communicates upstream to the MIDAS-TRANS transmitter or MIDAS-C controller, which aggregates alarm states and forwards structured data to the site-level DCS or safety PLC. This layered signal flow ensures that gas concentration readings are not only captured at the field level but are also available for logic processing, historian archiving, and operator visualization at every tier of the automation pyramid.

Product Specification Table

System Compatibility Notes

The MIDAS-2MLQ achieves its full potential when integrated within a coordinated system architecture. At the controller level, the MIDAS-C Controller serves as the central processing unit for up to 32 MIDAS detector points, managing alarm thresholds, relay outputs, and Modbus RTU or BACnet communication to the site SCADA. The MIDAS-TRANS Transmitter provides a 4–20 mA analog output interface for legacy DCS systems that do not support digital fieldbus protocols, ensuring backward compatibility across mixed-generation control platforms.

On the power layer, the MIDAS-PS Power Supply Module delivers regulated 24 VDC to the detector backbone, with built-in surge protection and brownout detection. For redundant power architectures, dual MIDAS-PS units can be configured in parallel, ensuring that a single power supply failure does not interrupt gas monitoring continuity — a critical requirement in SIL-rated safety instrumented systems.

At the I/O and relay layer, the MIDAS-RB Relay Board provides hardwired alarm outputs for local audible and visual annunciators, ventilation interlock systems, and emergency shutdown (ESD) triggers. These relay outputs are configurable per zone and per alarm level (Warning, Alarm 1, Alarm 2, STEL, TWA), enabling precise integration with the site’s safety logic controller, such as a Honeywell Safety Manager or a third-party SIL 2-certified PLC.

For network integration, the MIDAS platform supports Modbus RTU and BACnet MS/TP communication protocols, allowing the MIDAS-C controller to interface directly with building management systems (BMS), distributed control systems (DCS), or industrial Ethernet gateways. Where Ethernet connectivity is required, a Modbus TCP/IP Gateway can be inserted between the MIDAS controller and the plant network, enabling real-time gas data to be streamed to historian servers, cloud-based monitoring platforms, or remote operations centers.

At the human-machine interface layer, the MIDAS-D Display Module provides a local LCD readout of gas concentration, alarm status, and fault codes for each detector point. For centralized visualization, the MIDAS system integrates with Honeywell’s Experion PKS or third-party SCADA platforms via OPC-DA or OPC-UA data bridges, enabling operators to monitor all gas detection points from a unified control room display. Trend data, alarm logs, and calibration records are automatically archived, supporting regulatory compliance and audit readiness.

For field execution, the MIDAS-2MLQ works in conjunction with MIDAS Sensor Cartridges — including the MIDAS-S-HCL for hydrogen chloride, MIDAS-S-NH3 for ammonia, and MIDAS-S-CO for carbon monoxide — allowing a single detector housing to be reconfigured for different target gases simply by swapping the cartridge. This modularity dramatically reduces spare parts inventory requirements and simplifies field maintenance procedures, as technicians need only stock a single detector model and a range of application-specific cartridges.

Industrial Application Notes

The MIDAS-2MLQ is deployed across a wide range of process industries where continuous gas monitoring is a regulatory and operational requirement. In petrochemical and refinery applications, the module is installed in compressor houses, pump stations, and storage tank farms to detect hydrocarbon vapors, hydrogen sulfide, and toxic process gases. Its IP66-rated housing and ATEX/IECEx certification make it suitable for Zone 1 and Zone 2 hazardous area classification, where ignition-protected equipment is mandatory.

In power generation facilities, including gas turbine plants and combined heat and power (CHP) stations, the MIDAS-2MLQ monitors for natural gas leaks in turbine enclosures and fuel gas conditioning skids. Its integration with the plant DCS via Modbus RTU allows gas alarm states to be incorporated into the turbine control logic, enabling automatic fuel isolation in the event of a confirmed gas release.

In water and wastewater treatment plants, the module is used to monitor chlorine, hydrogen sulfide, and ammonia in chemical dosing rooms, pump stations, and digester buildings. The MIDAS system’s ability to support multiple gas types within a single network simplifies the instrumentation architecture for facilities that handle a diverse range of hazardous chemicals.

In mining and metallurgical operations, the MIDAS-2MLQ is deployed in underground headings, crusher buildings, and smelter control rooms to detect carbon monoxide, sulfur dioxide, and nitrogen dioxide. Its robust construction and wide operating temperature range ensure reliable performance in the harsh environmental conditions typical of mining and heavy industry.

In pharmaceutical and food processing facilities, the module monitors for ammonia refrigerant leaks in cold storage areas and carbon dioxide accumulation in fermentation and carbonation zones. Its compliance with international safety standards supports the facility’s overall process safety management (PSM) program and insurance requirements.

Product Compatibility FAQ

Q1: Is the MIDAS-2MLQ (SKU: 2MLQ-TR1C-CC) compatible with existing MIDAS-C controllers and MIDAS-TRANS transmitters already installed in my facility?
A: Yes. The MIDAS-2MLQ is fully compatible with all generations of the MIDAS-C controller and MIDAS-TRANS transmitter. It connects via the standard MIDAS detector backbone and is automatically recognized by the controller during system initialization. No firmware upgrade is required for most installations, though it is recommended to verify the MIDAS-C firmware version against Honeywell’s compatibility matrix for the specific cartridge type being used. All units supplied by ZYPLC are tested for communication handshake and alarm response prior to shipment, and are covered by a Warranty and support terms confirmed before quote.

Q2: Can the MIDAS-2MLQ be integrated into a SIL 2-rated safety instrumented system (SIS), and what additional components are required?
A: The MIDAS platform, including the MIDAS-2MLQ, is designed for use in safety-related applications and carries relevant functional safety certifications. For formal SIL 2 integration, the MIDAS-2MLQ is typically used as the field sensing element, with its 4–20 mA or relay output connected to a certified safety logic controller such as the Honeywell Safety Manager or an equivalent SIL 2-rated PLC. The safety logic controller performs the SIL-rated voting and shutdown logic, while the MIDAS system handles gas concentration measurement and local alarming. A full SIL assessment, including proof test interval and diagnostic coverage calculations, should be performed by a qualified functional safety engineer for each specific application.

Q3: What is the recommended maintenance and calibration schedule for the MIDAS-2MLQ in a continuous process environment, and how does the Warranty and support terms confirmed before quote apply?
A: Honeywell recommends a bump test (functional response test) every 3 months and a full calibration every 6 months for most industrial applications, with more frequent intervals in environments with high gas exposure or extreme temperature cycling. The MIDAS-2MLQ’s on-board diagnostics continuously monitor sensor health, power supply integrity, and communication status, generating fault codes that are displayed locally and transmitted to the MIDAS-C controller. ZYPLC’s Warranty and support terms confirmed before quote covers manufacturing defects and verified functional failures under normal operating conditions. Units that fail within the warranty period are replaced or repaired at no additional cost, with expedited processing to minimize system downtime. Customers are encouraged to maintain calibration records as part of their preventive maintenance program to support warranty claims and regulatory audits.