Honeywell 621-9939-C Serial Link Module

The Honeywell 621-9939-C Serial Link Module is an industrial-grade communication interface module designed for use in Honeywell’s robust PlantScape and TPS (TotalPlant Solution) Distributed Control Systems (DCS). This module provides a reliable and high-speed serial communication link between external intelligent devices (RTUs, PLCs, analyzers, etc.) and the Honeywell control system, enabling real-time data exchange, system integration, and advanced process automation.

Built for mission-critical environments, the 621-9939-C supports multiple serial protocols, allowing seamless interoperability across diverse industrial networks. Its high-performance architecture and durable construction make it a trusted choice in sectors like refining, chemical processing, power generation, and water treatment facilities.

Product Specifications

Product Applications

The 621-9939-C module is used in various industrial automation and process control scenarios, particularly in high-demand, real-time systems:

• SCADA and DCS Communication: Acts as an interface for SCADA and DCS to communicate with remote RTUs or PLCs.

• Industrial Protocol Integration: Integrates third-party devices into Honeywell systems using standard protocols such as Modbus.

• Data Acquisition Systems: Collects and transmits real-time data from analyzers, flow computers, or legacy controllers.

• Refinery and Chemical Plant Monitoring: Enhances visibility and control over distributed assets in large-scale facilities.

• Power Plant Automation: Helps streamline communication with protection relays, load controllers, and substation gear.

• Water Treatment Facilities: Allows centralized monitoring of remote pumping stations and treatment units.

Product Advantages

• High Protocol Flexibility: Supports multiple serial communication standards and protocols, ensuring easy integration.

• Enhanced Reliability: Industrial-grade design ensures stable operation in harsh environments.

• Real-Time Data Exchange: Enables fast and accurate data transfer for time-sensitive control processes.

• Seamless Integration with TPS/TDC Systems: Fully compatible with Honeywell’s legacy and modern DCS platforms.

• Comprehensive Diagnostics: LED indicators and built-in test functions simplify troubleshooting and maintenance.

• Upgradeable Firmware: Protects investment and allows adaptation to future communication needs.

• Compact Form Factor: Saves panel space while delivering powerful communication functionality.

FAQ

1. What serial communication protocols are supported by the 621-9939-C?

   The module supports RS-232, RS-422, RS-485, Modbus RTU/ASCII, and Honeywell proprietary protocols.

2. Is the module compatible with Modbus TCP/IP?

   No, the 621-9939-C is a serial link module and supports only serial-based Modbus (RTU/ASCII), not Ethernet-based Modbus.

3. Can this module be used with third-party PLCs?

   Yes, it can interface with third-party PLCs that support standard serial protocols such as Modbus or ASCII.

4. How is firmware updated on the 621-9939-C?

   Firmware can be updated through the host Honeywell control system using system tools with proper access rights.

5. Does the module support communication redundancy?

   It supports serial communication redundancy through proper network topology and dual port configurations.

6. Can the module be hot-swapped during operation?

   No, the module should be powered down or the system placed in maintenance mode before removal or insertion.

7. What diagnostic capabilities are available?

   The module includes built-in self-tests, TX/RX activity LEDs, and error/fault status indicators.

8. Is the baud rate configurable?

   Yes, the baud rate is software configurable via system integration tools and depends on the connected devices.

9. What is the maximum communication distance supported?

   For RS-485, the maximum cable length is approximately 1,200 meters (4,000 feet), depending on baud rate and cable type.

10. Can the module handle multiple devices on one serial link?

    Yes, in RS-485 multi-drop configuration, it can communicate with multiple slave devices using proper addressing.