Honeywell Enraf S0888105 CIU888 RS232/485 Field Board

Honeywell Enraf S0888105 CIU888 RS232/485 Communication Card (Field Board)

The Honeywell Enraf S0888105 is a serial communication field interface board engineered exclusively for the Honeywell Enraf CIU 888 (Communication Interface Unit). Operating as an essential telemetry link within bulk liquid storage terminals, marine tanker cargo systems, and refinery tank farms, the S0888105 board expands the CIU 888 system’s field bus and host connectivity.

This modular daughterboard provides galvanic isolation and field conditioning for bidirectional data acquisition across legacy serial field devices and upstream Supervisory Control and Data Acquisition (SCADA) / Distributed Control Systems (DCS). Configurable for EIA-232 (RS-232) point-to-point links or robust EIA-485 (RS-485) multi-drop industrial topologies, the S0888105 communicates using industry-standard serial protocols such as Modbus RTU, Modbus ASCII, and Honeywell Enraf GPU (Gauging Protocol Unit) formats.

Built to handle harsh industrial plant and coastal marine conditions, it guarantees continuous 24/7 inventory polling, custody transfer data processing, and critical tank level transmission without transmission drops or ground-loop corruption.

Technical Specifications

Key Features

1. Dual-Standard Serial Flexibility: Jumper/software-configurable support for both RS-232 full-duplex communication and RS-485 2-wire / 4-wire differential signaling up to 115.2 kbps.
2. Galvanic & Surge Protection: High-dielectric onboard transient absorption protection protects sensitive CIU 888 backplane electronics against induced line surges, ground loops, and lightning interference common to tall tank structures.
3. Protocol Interoperability: Native hardware translation supporting Honeywell Enraf GPU, Modbus RTU Master/Slave, and CIU 880/858 legacy emulation layers.
4. Modular Hot-Swappable Maintenance: Engineered specifically for slot integration within the 6-slot CIU 888 expansion bay, cutting replacement downtime during planned or unscheduled automation outages.
5. Industrial Marine & Terminal Grade: Conformal-coated PCB construction designed to resist saline atmospheres, moisture condensation, and constant vibration on maritime vessels and petrochemical storage facilities.

Mainframe Host Compatibility

• Honeywell Enraf CIU 888 Prime, Plus, and Advanced Series Communication Interface Units.
• Fully supported across CIU 888 expansion bay slots (Option Slots 1 through 6).

Downstream Gauging Equipment Compatibility

• Radar Level Gauges: SmartRadar FlexLine 990, SmartRadar Pro 873, SmartRadar Essential 877, SmartRadar Guide 894.
• Servo Gauges: Enraf 854 ATG, Enraf 854 XTG.
• Inventory Transmitters & Interfaces: VITO 762 (Temperature & Water Bottom), 866 VPU (Valve Positioner Unit), 872 HLS (Hybrid Level Sensor).
• Third-Party Compatibility: Modbus-compliant field devices and Emerson/Saab TRL/2 loops (via secondary loop configuration/converters).

Applications

• Petroleum & Chemical Storage Terminals: High-speed polling of multi-drop tank farm radars measuring Level, Free Water, and Multi-Spot Average Temperature (VITO).
• Marine Cargo Handling (Tankers & FPSOs): Critical cargo tank monitoring, custody transfer bunkering, and ballast liquid monitoring on crude carriers, chemical parcel tankers, and product vessels.
• Refinery Inventory Automation: Interfacing tank level radar loops to plant DCS systems (Honeywell Experion PKS, Yokogawa CENTUM, Emerson DeltaV).
• Pipeline Terminals & Off-Site Facilities: Intermediate booster station tankage telemetry via Modbus master serial polling interfaces.

Frequently Asked Questions

What is the primary function of the Honeywell Enraf S0888105 board?

The S0888105 is an internal serial communication field board designed for the Honeywell Enraf CIU 888 Communication Interface Unit. It provides RS-232 and RS-485 communication channels that allow the CIU 888 to poll field tank gauging devices (radar, servo, temperature) or transmit compiled inventory data to host control systems such as DCS and SCADA.

Can the S0888105 be used in older CIU 880 or CIU 858 platforms?

No. The S0888105 is form-factor, voltage, and backplane-specific to the modern CIU 888 platform. For older CIU Prime or CIU Plus models, the corresponding predecessor boards (such as S0880811 or S0880813) must be utilized.

How do I configure the card between RS-232 and RS-485 operational modes?

Operating modes are selected through internal hardware jumpers located on the board surface and confirmed via the software communication profiles in the CIU 888 web configuration tool. Always ensure the jumper layout matches your loop physical interface before powering up the unit.

How many field instruments can be connected to a single S0888105 port in RS-485 mode?

In standard RS-485 multidrop configurations, the port supports up to 32 standard electrical unit loads. The actual number of supported tank gauges per port typically ranges between 10 and 16 instruments, depending on field cable length, baud rate, and required real-time scan cycle times.

What causes communication timeout errors on this board after a field replacement?

The most frequent causes include mismatched baud rate / parity settings in the CIU 888 software profile, reversed polarity on the differential data pair (A/B or +/-), missing or double-installed 120 Ω end-of-line termination resistors, or ground potentials exceeding the transceivers’ common-mode rejection threshold.

Is dynamic firmware flashing required when replacing an S0888105 board?

No dedicated firmware flash is required for the card itself. The CIU 888 mainframe operating system recognizes the peripheral card via internal backplane enumeration and applies the host’s stored configuration directly to the hardware upon system boot.