Technical Specifications

FAQ

1. What is the primary function of the Foxboro FCM100Et P0926GS Communication Module?

The FCM100Et P0926GS is a redundant fieldbus communications module designed for Foxboro I/A Series distributed control systems. Its main function is to provide the communication interface between DIN-rail-mounted Fieldbus Modules and the Z-Module Control Processor over the MESH control network. The module converts communication between the 100 Mbps MESH control network and the 2 Mbps HDLC Module Fieldbus used by compatible FBMs. This allows field I/O data to be transferred reliably between distributed field devices and the higher-level DCS control architecture. In redundant installations, two FCM100Et modules can operate together using a Master/Tracker arrangement to improve communication availability.

2. What communication speeds does the FCM100Et support?

The FCM100Et provides a 100 Mbps MESH control network interface and a 2 Mbps HDLC Module Fieldbus interface. The module performs the required communication conversion between these two network levels, allowing compatible FBMs to exchange process data with the control processor. The different communication rates are part of the system architecture and are not simply selectable operating speeds. When troubleshooting communication performance, both sides of the interface should therefore be considered, including the fiber-optic network, FCM100Et module, fieldbus connections, and associated FBMs. A problem on either communication path can affect the availability of field I/O data at the controller.

3. How does redundancy work with the FCM100Et P0926GS?

The FCM100Et supports redundant operation using two modules installed as a pair. One module operates as the Master, handling the active communication function, while the second operates as the Tracker, monitoring the process and remaining synchronized with the active module. If the system detects a failure in the active communication path or module, the Master/Tracker roles can automatically reverse so that the standby module assumes the active role. This arrangement reduces the effect of a single module failure on DCS communication. For redundant installations, the two modules must be installed in the appropriate adjacent odd/even baseplate positions and connected through the corresponding splitter/combiner arrangement.

4. What type of fiber-optic connection does the FCM100Et use?

The FCM100Et uses a multimode fiber-optic connection with 62.5/125 μm multimode fiber and ceramic LC-type connectors. The fiber interface provides the connection between the communication module and the MESH control network while providing electrical isolation between network sections. Supported fiber cable lengths can range from approximately 3 meters to 2 kilometers, depending on the installation configuration and system requirements. For longer cable runs, the appropriate fiber specification should be selected carefully, and the connectors should be kept clean and properly seated. Excessive optical loss, damaged fiber, or contaminated connectors can cause intermittent communication or complete network link failure.

5. Can the FCM100Et P0926GS be used for time synchronization?

Yes. The FCM100Et supports an optional GPS time-strobe function for applications requiring accurate event timing. This capability can be used to synchronize supported Transient Data Recorder, Transient Data Analysis, and Sequence of Events Fieldbus Modules. Under supported conditions, synchronization can achieve accuracy of approximately 1 millisecond. This feature is particularly useful in industrial process applications where the exact timing of events must be recorded for sequence analysis or troubleshooting. When time synchronization is not functioning correctly, the GPS source, synchronization wiring, module configuration, and associated SOE or TDR/TDA equipment should be checked as a complete system.

6. Where can the FCM100Et P0926GS be installed?

The FCM100Et is mounted on a compatible Modular Baseplate, which can be installed horizontally or vertically. Modular Baseplates are available in 2-, 4-, and 8-position configurations. For redundant operation, the two FCM100Et modules are installed in an odd slot and the immediately adjacent even slot, such as positions 1 and 2, 3 and 4, 5 and 6, or 7 and 8. The baseplate itself can be mounted on a DIN rail or installed in a 19-inch rack using the appropriate mounting hardware. Correct slot positioning is important for redundant operation because the paired modules must occupy the designated adjacent positions.

7. What should be checked if the FCM100Et loses communication with the DCS?

Communication troubleshooting should begin by determining whether the fault affects one FCM100Et module, the redundant pair, a group of FBMs, or the entire communication network. The module’s power supply and seating on the Modular Baseplate should be checked first. Next, inspect the multimode fiber-optic cables and LC connectors for contamination, damage, poor connection, or excessive optical loss. The 100 Mbps MESH network side and 2 Mbps HDLC Module Fieldbus side should then be checked separately to determine where communication is being interrupted. In a redundant configuration, the active Master and standby Tracker status should also be verified. If the standby module does not assume the active role following a detected failure, the redundancy configuration, interconnection hardware, and module status should be investigated.

8. What precautions should be taken when installing or replacing the FCM100Et?

Before replacing an FCM100Et, the DCS maintenance procedure should be followed to ensure that the relevant communication and control functions are placed in a safe maintenance state. The module should be handled using appropriate ESD precautions because it contains sensitive electronic circuitry. During installation, verify that the FCM100Et is positioned correctly on the Modular Baseplate and that the module is fully seated. For redundant systems, confirm that the two modules occupy the correct adjacent odd/even positions and that the splitter/combiner and fiber connections are correctly installed. Fiber-optic connectors should be kept clean and protected from contamination during maintenance. After installation, verify module power, Master/Tracker status, fiber communication, fieldbus communication, and DCS diagnostics before returning the system to normal operation.