Description

The Emerson CON021 is a specialized serial communication interface module designed for the Emerson DeltaV distributed control system (DCS), enabling robust connectivity between the DeltaV controller and third-party field devices, legacy PLCs, analyzers, or auxiliary equipment that utilize standard serial protocols. As part of the DeltaV M-series I/O architecture, the Emerson CON021 serves as a protocol gateway—translating data between DeltaV’s native FOUNDATION Fieldbus or Ethernet-based control layer and external RS-232/RS-485 devices using Modbus RTU, ASCII, or proprietary command sets. This capability makes the Emerson CON021 indispensable in hybrid automation environments where full system replacement is impractical or cost-prohibitive.

Deployed within the DeltaV I/O carrier chassis alongside analog and digital modules, the Emerson CON021 integrates seamlessly into the DeltaV Studio engineering environment. Engineers can configure baud rate, parity, stop bits, and message templates directly in the control configuration, eliminating the need for external protocol converters or custom middleware. With built-in electrical isolation and surge protection, the Emerson CON021 ensures signal integrity in electrically noisy industrial settings such as compressor stations, refineries, and power plants—where reliable data exchange is critical for safety, efficiency, and regulatory compliance.

Technical Specifications

Main Features and Advantages

Flexible protocol support for heterogeneous plant integration:
The Emerson CON021 eliminates communication silos by allowing DeltaV systems to directly interrogate non-Emerson devices—such as turbine controllers, gas chromatographs, flow computers, or older PLCs—without intermediate gateways. Its configurable message buffers and response timeout handling ensure stable polling even with slow-responding instruments, a common challenge in refinery analyzer shelters or offshore platforms.

Robust industrial design with electrical resilience:
Unlike generic USB-to-serial adapters, the Emerson CON021 features galvanic isolation between the DeltaV backplane and field wiring, protecting the controller from ground loops, voltage spikes, and lightning-induced transients. The module’s conformal-coated PCB and metal-shielded housing meet stringent EMC requirements, ensuring years of trouble-free operation in high-EMI environments near VFDs or switchgear.

Native DeltaV integration reduces engineering overhead:
Because the Emerson CON021 is recognized as a standard I/O type within DeltaV Studio, engineers can map serial data points directly to control strategies, alarms, and historian tags—just like any analog input. No external drivers, OPC servers, or scripting are required. This tight integration accelerates commissioning, simplifies troubleshooting, and maintains full audit trail compliance for regulated industries.

Redundancy-ready for critical applications:
When used with redundant DeltaV M-series controllers, the Emerson CON021 supports automatic failover of serial communications. While only one module is active at a time, the standby controller maintains synchronization of configuration and connection state, ensuring uninterrupted data flow during controller switchover—a vital feature for continuous processes like ethylene cracking or LNG liquefaction.

Long-term availability for lifecycle management:
Despite being a mature product, the Emerson CON021 remains actively supported due to its widespread use in installed DeltaV bases worldwide. For asset owners modernizing brownfield sites, it provides a cost-effective path to retain valuable legacy assets while migrating core logic to DeltaV—extending equipment life without compromising cybersecurity or operational visibility.

Application Field

The Emerson CON021 is widely used in oil & gas upstream and midstream operations, where it connects DeltaV systems to third-party wellhead controllers, multiphase flow meters, and cathodic protection units via Modbus RTU over long-distance RS-485 links. In natural gas compressor stations, the Emerson CON021 interfaces with legacy turbine control panels (e.g., from Wood Group or Rolls-Royce) to retrieve speed, vibration, and trip status—enabling centralized monitoring without replacing the entire drivetrain control system.

In chemical and pharmaceutical manufacturing, the Emerson CON021 integrates laboratory analyzers, pH/ORP transmitters, and batch recorders that output ASCII strings over RS-232. By capturing this data directly into DeltaV, plants achieve full electronic batch records (EBR) compliant with 21 CFR Part 11, eliminating manual transcription errors. Similarly, in power generation, the Emerson CON021 retrieves breaker status, transformer tap positions, and generator excitation data from protective relays that lack Ethernet interfaces.

Water treatment facilities also benefit from the Emerson CON021, using it to poll chlorine residual analyzers, ultrasonic level sensors, and SCADA RTUs from municipal networks. Because the module supports both master and slave Modbus roles, it can act as either a data collector or a remote terminal unit—offering architectural flexibility. Across all these sectors, the Emerson CON021 delivers a proven, secure, and maintainable bridge between the digital present and the analog past.

Related Products

• CON011: Earlier DeltaV serial module with limited protocol support; CON021 is its enhanced successor

• MIO021: Multi-function I/O module that includes analog/digital channels alongside basic comms

• CHARM I/O: Next-generation DeltaV I/O architecture; CON021 is not compatible—used only in M-series

• DeltaV M5 Controller: Primary host controller for CON021 in non-redundant configurations

• DeltaV M5-RR: Redundant controller pair that supports failover with CON021 modules

• RS-485 Terminal Block (TB-CON021): Dedicated wiring accessory for clean field connections

• FOUNDATION Fieldbus H1 Card: Alternative I/O for smart devices; CON021 complements it for non-FF gear

• DeltaV SIS: Safety system; CON021 is not SIL-rated and must be isolated from safety-critical loops

• AMS Device Manager: Emerson asset management software; CON021 data can be routed through DeltaV to AMS

• Modbus TCP Gateway (e.g., ProSoft MVI56-MCM): External alternative when CON021 slots are exhausted

Installation and Maintenance

Pre-installation preparation: Before installing the Emerson CON021, confirm that your DeltaV M-series I/O carrier has available slots and that the firmware version supports the module (minimum DeltaV v12). Power down the I/O chassis and follow site-specific lockout procedures. Insert the Emerson CON021 into the designated slot, ensuring the ejector lever is fully seated to establish solid backplane contact. Use shielded, twisted-pair cable for field connections, grounding the shield at the controller end only to avoid ground loops. Verify terminal torque per Emerson specifications (typically 0.5–0.6 N·m).

Maintenance recommendations: During routine checks, inspect the Emerson CON021’s front-panel LEDs—green indicates power and backplane communication, while a blinking red may signal framing errors or timeout faults. Use DeltaV Diagnostics to monitor CRC errors, retry counts, and response latency. If communication becomes intermittent, check for loose terminals, incorrect baud rate settings, or excessive cable length (>1200 m for RS-485). Avoid hot-swapping the Emerson CON021 unless the system is explicitly configured for it, as unexpected disconnection may cause controller scan faults. Store spare modules in static-safe packaging away from magnetic fields and extreme temperatures.