HOLLYSYS FM100 Series Modules: FM131A-B & Full Range

Technical Dossier

Product Details And Specifications

HOLLYSYS FM100 Series: Comprehensive Module Range and Technical Overview

The HOLLYSYS FM100 Series is a core product line within the MACS (Maxi-DCS Automation Control System) distributed control system platform, developed by HOLLYSYS Automation Technologies. This series has established a significant installed base across heavy industrial sectors globally, including petrochemical refineries, coal chemical plants, nuclear power auxiliary systems, and large-scale thermal power generation facilities in China and Southeast Asia. The FM100 architecture is designed around a redundant backplane bus topology, supporting hot-standby controller configurations and deterministic I/O scanning cycles critical for continuous process control. Its modular design allows engineering teams to configure systems ranging from small standalone controllers to large multi-node DCS networks with thousands of I/O points.

The Evolution of FM100 Series Architecture

The FM100 Series was introduced as part of HOLLYSYS's second-generation MACS platform, succeeding earlier proprietary control hardware. The initial architecture centered on the FM131 main control unit operating over a dedicated system bus (SBUS) with separate I/O expansion racks. Subsequent revisions introduced the FM131A and FM131A-B variants, incorporating enhanced processor performance, expanded onboard memory, and improved redundancy switching logic with sub-100ms failover times.

The series evolved to support PROFIBUS-DP and Modbus RTU field device integration via dedicated communication adapter modules, addressing the growing need for hybrid DCS-fieldbus architectures in brownfield plant upgrades. Later additions to the FM100 catalog included high-density analog I/O modules and intrinsically safe I/O interfaces for hazardous area installations. As the MACS V platform (based on the HOLLiAS architecture) became HOLLYSYS's primary offering from approximately 2015 onward, the FM100 Series transitioned into a mature/legacy lifecycle phase. Installed base units remain operational across thousands of process control loops, creating sustained demand for spare parts, repair services, and lifecycle extension support.

FM100 Series Full Catalog & Functionalities (SKU List)

Controllers & Main Processing Units

• FM131A-B: Main control unit, redundancy-capable, SBUS master, onboard Ethernet port
• FM131A: Main control unit, standard configuration, single Ethernet interface
• FM131: First-generation main controller, legacy SBUS protocol, no Ethernet
• FM148: Redundant controller module, hot-standby pair configuration support

Digital Input (DI) Modules

• FM151A: 16-channel 24VDC digital input, isolated, DIN rail mount
• FM151B: 32-channel 24VDC digital input, high-density, dual-row terminal
• FM152: 16-channel 120VAC digital input, optocoupler isolated
• FM153: 16-channel dry contact digital input, for field switch interfaces

Digital Output (DO) Modules

• FM161A: 16-channel 24VDC digital output, transistor type, 0.5A per channel
• FM161B: 32-channel 24VDC digital output, high-density configuration
• FM162: 8-channel relay output, 2A per channel, for motor starter interfaces

Analog Input (AI) Modules

• FM171A: 8-channel 4–20mA analog input, 16-bit resolution, HART pass-through
• FM171B: 16-channel 4–20mA analog input, multiplexed, standard process signals
• FM172: 8-channel thermocouple input, multi-type (K, J, T, E, R, S, B), cold junction compensated
• FM173: 8-channel RTD input, PT100/PT1000, 3-wire and 4-wire configurations

Analog Output (AO) Modules

• FM181A: 8-channel 4–20mA analog output, 12-bit resolution, loop-powered
• FM181B: 4-channel 4–20mA analog output with HART communication support

Communication & Network Modules

• FM191: PROFIBUS-DP master adapter, supports up to 125 slave devices per segment
• FM192: Modbus RTU/ASCII master-slave communication module, RS-485 interface

Power Supply Modules

• FM141A: 24VDC system power supply module, 10A output, redundancy-capable
• FM141B: 24VDC redundant power supply module, hot-swap supported

Sourcing Hard-to-Find & Obsolete FM100 Series Parts

As the FM100 Series has entered its mature lifecycle phase, HOLLYSYS has progressively reduced factory production of legacy modules in favor of the HOLLiAS MACS V platform. This creates a documented supply gap for plant operators running FM100-based DCS systems who require spare modules for corrective maintenance, preventive replacement, or system expansion without full platform migration.

DriveKNMS maintains a dedicated inventory program for FM100 Series components sourced through authorized secondary market channels, decommissioned plant buybacks, and certified refurbishment pipelines. Our stock covers both current-production variants (FM131A-B, FM171A, FM181A) and discontinued models (FM131, FM152, FM162) that are no longer available through standard HOLLYSYS distribution. All sourced units are subject to full functional verification before dispatch. For plant operators requiring long-term maintenance agreements or bulk spare part packages for FM100 installations, DriveKNMS provides multi-year supply contracts with guaranteed lead times.

Quality Control for the FM100 Series Range

FM100 Series modules utilize a proprietary backplane bus interface with specific signal timing requirements that differ from standard industrial bus protocols. Standard bench testing procedures are insufficient to validate correct SBUS communication behavior, redundancy switching logic, and I/O channel calibration accuracy.

DriveKNMS applies a dedicated FM100 test protocol that includes: powered backplane insertion testing to verify bus arbitration and address recognition; channel-by-channel I/O verification against factory calibration tolerances (±0.1% for analog modules); redundancy switchover simulation for FM131A-B and FM148 controller pairs; communication adapter loopback testing for FM191 and FM192 modules; and thermal soak testing at 55°C for 4 hours to screen latent component failures. All test results are documented and supplied with each unit. Modules that fail any test stage are quarantined and not returned to inventory.