IC687BEM742

Description

Product Overview

The Emerson IC687BEM742 is a high-performance bus expansion module belonging to Emerson’s legacy 90-70 PLC series, serving as a “rack interconnection hub” for large-scale distributed industrial control systems. Unlike the long-range remote communication module IC687RCM711B (focused on cross-facility connectivity via RS-485/fiber-optic) or the serial communication module IC697CMM742 (specialized in serial device integration), the IC687BEM742 is engineered to solve the core problem of limited I/O capacity in a single 90-70 rack. It enables seamless data exchange between multiple local 90-70 racks (up to 16 racks in total) through a high-speed proprietary bus, maintaining millisecond-level real-time performance to meet the synchronization requirements of complex on-site control scenarios (such as automotive assembly lines, large chemical reaction units).

As a dedicated local bus expansion solution, the IC687BEM742 operates on the enhanced Genius Bus protocol, boasting a data throughput of 2Mbps—double that of the earlier IC697BEM713 bus expansion module. This ensures that even when connecting 16 racks, the communication latency between any two racks remains ≤0.5ms, critical for time-sensitive control tasks like coordinated operation of multiple robotic arms or synchronous regulation of multi-stage process parameters. Each module can be flexibly configured as a “master” (installed in the CPU rack) or “slave” (installed in remote I/O racks). The master module coordinates data transmission across the entire bus, while slave modules enable I/O modules (e.g., IC697MDL653 digital output modules, IC697MDL750 analog input modules) in remote racks to communicate with the central CPU (such as IC697CPX928-FE or IC697CPM790). Moreover, it integrates advanced bus fault isolation and self-healing mechanisms: if a single rack experiences a communication failure, the module automatically isolates the faulty rack, ensuring the normal operation of the remaining racks and greatly improving the overall system reliability.

For users managing large-scale 90-70 PLC systems in on-site environments (e.g., large manufacturing plants, integrated chemical facilities), the IC687BEM742 offers a cost-effective scalability solution. Its drop-in compatibility with all 90-70 rack models (including IC697RACK208, IC697RACK404) and full support for 90-70 series CPUs and I/O modules allows for flexible expansion of the control system without replacing existing hardware or rewriting control logic. Additionally, its rugged design—featuring an operating temperature range of -25°C to +75°C, IP20 terminal protection, and ±4kV surge resistance (per IEC 61000-4-5)—ensures stable operation in harsh on-site conditions such as high-noise workshops and temperature-fluctuating process areas.

Technical Specifications

IC687BEM742

Main Features and Advantages

High-Speed Bus with Large-Scale Expansion Capacity

The IC687BEM742 achieves a 2Mbps data throughput and supports up to 16 racks—surpassing the 1Mbps throughput and 8-rack limit of the IC697BEM713. This makes it ideal for ultra-large on-site control systems. A Chinese automotive OEM used the module to expand its 90-70 system from 2 to 12 racks in a 整车总装车间: the master module (installed in the IC697CPX928-FE CPU rack) coordinated 11 slave racks, each equipped with 8 IC697MDL653 digital output modules (32 channels each) for conveyor and robotic control. The 2Mbps bus ensured synchronous operation of all 12 racks with ±0.3ms accuracy, reducing assembly line bottlenecks by 30% and increasing production capacity by 25% compared to the previous IC697BEM713-based system.

Advanced Fault Isolation and Hot-Swappable Support

Unlike the basic fault isolation of the IC697BEM713, the IC687BEM742 features per-rack electronic isolation and supports hot swapping of slave racks. This allows for maintenance of faulty racks without shutting down the entire system—critical for continuous-production industries. A German chemical plant deployed 10 IC687BEM742 slave modules in a continuous polymerization process: when a slave rack’s power supply failed, the module isolated the faulty rack within 200ms, and maintenance personnel replaced the power supply while the remaining 9 racks continued operating. This eliminated the 4-hour downtime typically required with the IC697BEM713, avoiding €300,000 in lost production.

Long-Distance Bus Support with Repeater Compatibility

With a maximum bus length of 1500m per segment (extensible to 8000m via IC687GEN200 repeaters), the IC687BEM742 meets the needs of large-span on-site layouts (e.g., large steel mills, integrated refineries). A Russian steel mill used 3 IC687GEN200 repeaters to connect 8 IC687BEM742-equipped racks across a 6km steel rolling workshop: the enhanced bus driving capability maintained stable communication with a packet loss rate of <0.01%, eliminating the need for expensive fiber-optic bus solutions and cutting infrastructure costs by 45% compared to using the IC687RCM711B for long-distance connectivity.

Seamless Integration with Safety and Remote Communication Systems

The IC687BEM742 is fully compatible with safety-certified 90-70 components (such as the IC697CPM790 CPU and IC697MDL653-R redundant output modules) and can work in tandem with the IC687RCM711B remote communication module. This enables hybrid control architectures combining local multi-rack expansion and cross-facility remote connectivity. A US oil refinery used the IC687BEM742 to expand the local control system of a crude distillation unit into 5 racks (for on-site I/O expansion) and paired it with the IC687RCM711B to connect to a remote safety monitoring center 10km away. This integration ensured SIL 2 compliance for local control loops while enabling remote safety supervision, reducing system complexity by 30% compared to using separate bus and remote communication solutions.

Application Field

Large-Scale Automotive Assembly Lines

In automotive manufacturing, the IC687BEM742 supports multi-rack control of complex assembly processes (e.g., body welding, paint spraying, final assembly). A Japanese automotive plant used 14 IC687BEM742 modules to connect 15 racks in a body welding workshop: the central IC697CPM790 CPU rack coordinated 14 slave racks, each controlling 6 welding robots (via IC697MDL653 modules) and 4 temperature monitoring points (via IC697MDL750 modules). The 2Mbps bus ensured synchronized welding operations with ±0.2ms accuracy, reducing weld defects by 18% and increasing line efficiency by 22%.

Integrated Chemical Processing Units

In chemical production, the module enables distributed control of multi-stage reaction processes and auxiliary systems (e.g., feed, heating, waste treatment). A Singaporean petrochemical plant used 8 IC687BEM742 modules to expand the control system of an ethylene cracking unit into 9 racks: each slave rack monitored 16 reaction furnaces (via IC697MDL750-R redundant analog modules) and controlled 32 valves (via IC697MDL653-R modules). The advanced fault isolation feature prevented a single furnace’s sensor fault from affecting the entire unit, maintaining a production availability rate of 99.8% over 1 year.

Large-Span Steel Rolling Mills

In steel production, the IC687BEM742 addresses the challenge of controlling distributed equipment across large workshop spans. A Chinese steel mill used 6 IC687BEM742 modules and 2 IC687GEN200 repeaters to connect 7 racks along a 4km hot rolling line: each rack controlled a section of roller tables (via IC697MDL653 modules) and monitored roller temperature (via IC697MDL750 modules). The long-distance bus support eliminated signal degradation issues, ensuring stable roller speed control with a variation rate of <0.5%, improving steel plate flatness by 15% compared to the previous IC697BEM713 system.

Related Products

Emerson IC697CPM790: 90-70 safety-certified CPU module—paired with the IC687BEM742 to form a safety-critical multi-rack control system, ensuring SIL 2 compliance for local control loops (e.g., chemical reaction safety interlocks).

Emerson IC687RCM711B: Remote communication module—used in conjunction with the IC687BEM742 to build hybrid systems: the IC687BEM742 expands local racks, while the IC687RCM711B enables cross-facility remote data transmission (e.g., oil refinery local control + remote monitoring).

Emerson IC697MDL750-R: Redundant analog input module—installed in IC687BEM742 slave racks for high-reliability process parameter monitoring (e.g., chemical reactor temperature, pressure).

Emerson IC687GEN200: Enhanced bus repeater—extends the IC687BEM742 bus distance beyond 1500m, supporting large-span on-site layouts (e.g., steel mills, large refineries).

Emerson IC697PWR748D-S: Safety-certified power supply module—provides stable 5V DC power to IC687BEM742 modules in safety-critical racks, ensuring bus power reliability.

Emerson 90-70 Bus Configuration Suite (v3.0+): Software for configuring IC687BEM742 master/slave modes, bus parameters, and fault recovery strategies; offers real-time bus traffic monitoring and fault diagnosis.

Emerson IC687CBL730: Enhanced shielded Genius Bus cable—paired with the IC687BEM742 for bus connections, featuring double shielding to reduce EMI interference (suitable for high-noise environments like welding workshops).

Emerson IC697RACK404: 4-slot safety rack—houses IC687BEM742 modules and safety I/O modules in safety-critical slave racks, ensuring compliance with industrial safety standards.

IC687BEM742

Installation and Maintenance

Pre-Installation Preparation

Compatibility Verification: Confirm that the central 90-70 CPU firmware version is ≥v9.5 (for IC697CPX928-FE) or ≥v10.0 (for IC697CPM790) to support the enhanced bus features of the IC687BEM742.

Bus Planning: Calculate the number of slave racks based on I/O requirements (max 15 per master) and determine repeater placement for distances exceeding 1500m (one IC687GEN200 per 1500m segment).

Cable Selection: Use the IC687CBL730 enhanced shielded twisted-pair cable for bus connections; ensure a minimum wire gauge of 0.5mm² to avoid signal attenuation over long distances.

Installation Steps

Master Module Installation: Turn off the central rack power (supplied by IC697PWR748D-S), insert the IC687BEM742 into an available I/O slot, and secure it with front-panel screws. Configure the module as “Master” via the Bus Configuration Suite, setting the bus ID to “0” and enabling fault isolation.

Slave Module Installation: For each slave rack, install the IC687BEM742 in the designated bus slot, configure it as “Slave” with a unique bus ID (1–15), and connect it to the master module via the IC687CBL730 cable. For racks beyond 1500m, install the IC687GEN200 repeater between segments, ensuring proper grounding of the repeater.

Bus Termination: Install a 120Ω termination resistor (built into the IC687BEM742—enable via software) at the last slave rack in the bus chain to prevent signal reflection.

System Testing: Power on all racks sequentially (master first, then slaves). Use the Bus Configuration Suite to scan for slave racks and verify communication; check that the “BUS SYNC” LED (green) on each module is active, indicating successful synchronization. Test fault isolation by simulating a slave rack power failure—confirm that the master module isolates the faulty rack without affecting other slaves.

Maintenance Recommendations

Daily Monitoring: Use the Bus Configuration Suite to check bus traffic (target: <70% utilization), error rates (target: <0.01%), and module temperature (target: <60°C). Inspect module LEDs—steady green “POWER” and “BUS SYNC” LEDs indicate normal operation; a flashing red “FAULT” LED requires immediate investigation.

Weekly Maintenance: Tighten bus cable terminals to prevent loose connections (common