The FC-IOTA-NR24 (also known as IOTA-NR24, part number 51306507-175) is a Honeywell field terminal assembly module, a non-redundant I/O terminal assembly unit designed specifically for use with RUSIO-3224 and RUSLS-3224 I/O modules. It is the core hardware within a safety management controller system that enables the interface between field signals and control modules.
This terminal assembly complies with IEC 61508 and IEC 61511 functional safety standards and can be applied up to SIL3 level operating conditions. It is widely used in process industries such as petrochemical, oil and gas, power, and chemical industries with safety interlocking requirements. The entire component integrates signal terminals, Ethernet communication interfaces, power supply circuits, and hardware function DIP switches, providing a one-stop solution for field cabling and connection of 32 general-purpose I/O channels, significantly simplifying cabling planning within the Safety Instrumented System (SIS) cabinet.
II. Core Functional Architecture and Hardware Design
The FC-IOTA-NR24 is equipped with three Weidmüller terminal blocks, clearly defining signal circuits: CN1 carries I/O signals from channels 1 to 16, CN2 carries I/O signals from channels 17 to 32, and CN3 provides four independent V+ power supply interfaces specifically for powering active analog input instruments. The negative terminals of CN1 and CN2 terminal blocks are connected to 0V, while the positive terminals correspond to independent signal channels, compatible with various general-purpose field I/O signal inputs.
For communication, it features two shielded RJ45 Ethernet interfaces, RIOLA and RIOLB, constructing a 100Mbps dual-link Ethernet communication channel, serving as Link A and Link B respectively, enabling data interaction between the I/O module and the safety controller. The hardware integrates a power toggle switch, enabling local control of module power-on and power-off. Reserved jumper positions for node addresses allow for setting device node addresses via dedicated jumper components. Hardware enable switching for ESD emergency shutdown is supported, with 32 channels offering flexible selection between general IO mode and ESD emergency stop input mode.
The component requires mounting on the MCAR-01 series metal mounting base, which integrates a grounding rail, a 24V DC power supply rail, and a 0V rail, providing a stable power supply and reliable grounding loop for the entire terminal assembly.
General Parameters
Model: FC-IOTA-NR24 (IOTA-NR24)
Operating Temperature: -40℃ ~ +70℃
Storage Temperature: -40℃ ~ +85℃
Relative Humidity: 10~95% (non-condensing)
Pollution Degree: Level 2 and above
Certifications: CE, UL, TUV
Power Supply: 24V DC, voltage fluctuation range -15%~+30%, maximum load 10A
Polarization Protection: Parallel diode reverse connection protection (fault-triggered fuse blows)
CN3 Four-way V+ pin total maximum current 1A, 0.7A operating voltage drop less than 1.5V, maximum reverse withstand voltage 36V
Built-in Fuse Specifications: 15A, 5×19mm blade DC fuse, rated DC voltage 32V, original model 0287015.PXS (Littelfuse)
Wiring Interface Parameters
24V Power Supply: 2 M4 screw terminals, connecting to the base power supply rail
Grounding Terminals: 8 M3.5 screws, connecting to the base metal housing
Ethernet: Shielded RJ45 interface
Terminal Brand/Model: Weidmüller BLZ 5.08 series terminals
Applicable Cable Cross-sectional Area: 0.50~2.50mm²
Stripping Length: 7mm
Tightening Torque: 0.5Nm
Physical Dimensions and Weight
Dimensions: 64mm × 120.7mm × 293.4mm
Net Weight: 0.46kg
IV. Supported IO Signal Types and Channel Configurations
The FC-IOTA-NR24 is compatible with all IO configuration modes of the RUSIO-3224 and RUSLS-3224 modules, enabling mixed deployment of digital and analog signals, covering most field instrument signal types in factories.
The digital signals include digital inputs with line monitoring, digital inputs without line monitoring, and a 32-channel dedicated line monitoring ESD emergency stop input. Digital outputs support 0.5A standard output and 1A/2A multi-channel outputs, all of which can enable or disable line diagnostic monitoring.
The analog circuitry supports 0~20mA and 4~20mA standard analog inputs and outputs. Four CN3 V+ power outputs are specifically designed to supply power to two-wire and three-wire active analog input instruments, ensuring stable power supply to the transmitter.
The device's ESD function supports hardware jumper switching. In the default jumper position, channel 32 is used as a general-purpose channel, freely configurable as analog/digital, input/output. When the jumper is switched to the enabled position, channel 32 is forcibly used as an ESD emergency shutdown input, requiring an external normally closed ESD switch with a 1kΩ series resistor.
V. Key Points for Node Address Jumpers and System Configuration Implementation
The entire terminal assembly relies on node address jumpers to define communication addresses. The jumpers are 10.2×10.2×6.1mm in size, made of gray plastic, and have a clearly printed two-digit number. Multiple jumper kits are provided to meet multi-site expansion needs: 51153818-201 (01~10), 51153818-202 (11~20), 51153818-203 (21~30), 51153818-204 (31~40).
During project implementation, the cabinet layout prioritizes the use of MCAR-01 metal mounting bases. All bases are uniformly grounded to avoid signal interference risks. Wiring operations strictly adhere to the 0.5Nm torque specification, and cable stripping length is controlled to 7mm to prevent loose connections and short circuits. During the cabling phase, communication cables and power cables should be distinguished. For RJ45 Ethernet, shielded network cables with complete grounding are recommended to reduce electromagnetic interference in industrial environments.
The entire hardware system supports SIL3 safety loop setup. All safety-related wiring loops require corresponding loop diagnostic functions to fully leverage Honeywell's safety control system fault detection capabilities.
Conclusion
The FC-IOTA-NR24 non-redundant I/O terminal block is a crucial bridge connecting controllers and field instruments in Honeywell's safety instrumented systems. Relying on its standardized hardware structure, extensive I/O compatibility, and the highest SIL3 functional safety level, it meets the signal access requirements of high-risk operating conditions in process industries. Unified terminal specifications and standardized mounting base design reduce the difficulty of cabinet cabling, while hardware jumper modes simplify on-site configuration and commissioning.
In existing plant upgrades and new SIS safety system projects, this terminal block effectively ensures the stability of field signal transmission and reduces the risk of interlocking system wiring failures. It is an indispensable piece of hardware for Honeywell's safety control systems in the chemical, power, and oil and gas industries. Sufficient spare parts reserves ensure rapid replacement in case of sudden hardware failures, shortening unplanned downtime and ensuring continuous and stable operation of production units. Spare Parts Procurement and Supply Instructions
FC-IOTA-NR24 (51306507-175) is a dedicated I/O terminal assembly for Honeywell safety control systems, widely used in aging SIS system expansion, system upgrades, and faulty spare part replacement scenarios.
For inventory verification, specification sheets, and project compatibility confirmation, please contact the relevant manager directly.
Manager: Leonia
Whatsapp: +8618030175807
FAQ (Frequently Asked Questions)
A: No, this terminal assembly must be used with a RUSIO-3224 or RUSLS-3224 module and must be installed on the MCAR-01 metal base to function properly.
Q2: Can all 32 channels of the IOTA-NR24 be used as ESD emergency stop circuits?
A: No, only channel 32 supports ESD input in terms of hardware; the remaining channels only support general-purpose IO configuration.
Q3: Can the V+ interface of CN3 directly drive a solenoid valve load?
A: It is not recommended. The total current limit of the four V+ pins of CN3 is 1A, mainly used to power small active instruments such as transmitters, and is not suitable for driving high-power loads.
Q4: What are the main differences between this product and the redundant version IOTA-R24?
A: FC-IOTA-NR24 is a non-redundant terminal assembly, adapted to a single-channel RUSIO module; the redundant model supports a dual-module redundant architecture. The hardware circuits and channel architectures of the two are not interchangeable, and the system architecture needs to be distinguished when purchasing.
Q5: Can the equipment operate continuously under an ambient humidity of 95%?
A: It can operate continuously under the condition of no condensation; when condensation occurs, it will cause terminal corrosion and short circuits, requiring the addition of a cabinet temperature control and dehumidification device.
