WCU Ship Control Unit Manual

Wiring requirements:

Wire diameter: 1.0-1.5 mm ² (18 AWG).

Polarity: Ensure that the positive and negative poles are correct; The module has built-in reverse protection.

Fuse: It is recommended to connect a 1A slow melting fuse (such as 5 × 20mm T1A) in series at the power input end.

Power supply precautions:

DC-DC boost to 24V is required in a 12V battery system, otherwise undervoltage will cause WCU to malfunction.

When the main power supply is cut off, the WCU should be able to maintain its internal configuration for at least 30 minutes (usually using non-volatile memory without battery backup).

3.2 Input/output interfaces (presumably based on typical control units)

Although the manual does not list the quantity of physical I/O, based on similar products, it is speculated that WCU may have:

Digital input: 8-16 channels, used to connect alarm contacts (temperature switch, pressure switch, float switch).

Analog input: 4-8 channels, 4-20mA or 0-10V, used to connect sensors (pressure transmitters, PT100, etc.).

Digital output: Relay output (2-4 channels), used for alarm lights and buzzers.

Communication interface: CAN bus, RS-485 (Modbus) or Ethernet, used for communication with K-Chief system or upper computer.

Wiring specifications:

The analog input uses shielded twisted pair cables, with the shielding layer grounded at one end.

If the relay output drives inductive loads (such as buzzers, contactor coils), it must be connected in parallel with a freewheeling diode or an RC absorption circuit.

Tighten the screws of all wiring terminals to a torque of 0.4 N · m and check them every six months.

Network and Communication Integration

WCU is usually used as the on-site node of the K-Chief integrated alarm system, connected to the main station (HMI or server) through redundant CAN bus or Ethernet.

4.1 CAN bus wiring

Bus type: twisted pair shielded wire, impedance 120 Ω (recommended Belden 3082A).

Topology: Main branch structure, with 120 Ω terminal resistors connected at both ends of the main line.

The length of the branch line is ≤ 6 meters.

The baud rate is usually 250 kbit/s (corresponding to 250 kbps).

Common problems and troubleshooting:

Unstable communication: Check if the terminal resistance is missing. Measure the resistance between CAN_S and CAN_L, which should be around 60 Ω.

No communication but normal resistance: Check if the power supply voltage is within the range of 18-32V and if the CAN transceiver is damaged (observe the waveform amplitude with an oscilloscope, CAN_S is about 2.5-3.5V, CAN_L is about 1.5-2.5V).

4.2 Ethernet connection (if any)

If WCU supports Ethernet, use CAT5e or higher shielded Ethernet cables to connect to switches or directly connect to K-Chief servers. The IP address needs to be on the same network segment as the system. Common troubleshooting:

Use the ping command to test connectivity, and check IP configuration, network cables, or switch ports if timeout occurs.

If packet loss is severe, check if the shielding layer is grounded and if the cable is routed parallel to the power line (maintaining a distance of at least 200mm).

Troubleshooting Guide

Based on on-site experience, the following are typical fault phenomena, possible causes, and solutions related to WCU.

5.1 WCU not working (power LED not lit)

Possible reasons:

The supply voltage is lower than 18V or higher than 32V.

Reverse power connection (although built-in reverse protection, long-term reverse voltage may cause damage).

The external fuse is blown.

The internal DC-DC converter is damaged.

Inspection steps:

Measure the voltage of the WCU power terminal with a multimeter, which should be between 19-30V.

Check the power fuse.

If the voltage is normal and the fuse is intact, but the LED does not light up, try disconnecting all external signal wires before powering on (excluding load short circuits). If it still doesn't light up, the module hardware is faulty and needs to be repaired or replaced.

5.2 Abnormal analog input readings (or constant maximum/minimum values)

Possible reasons:

The transmitter output circuit is open (reading 0 or very small).

The transmitter output is short circuited (reading at full range or abnormal).

An additional load is connected in series in the 4-20mA circuit.

The grounding loop causes common mode interference.

resolvent:

Connect an ammeter in series with the circuit to measure the actual current value. If it does not match the WCU display value, check the sampling resistance in the input circuit (usually 250 Ω or 100 Ω).

Confirm that the transmitter power supply is normal (two-wire transmitters require an external power source).

If using a three wire or four wire system, check if the common terminal is correctly connected to the AGND of WCU.

For the grounding loop, a signal isolator can be added to the signal loop.

5.3 Digital input status error (normally open/normally closed contacts read opposite)

Possible reasons:

The "NO/NC" logic setting in the software configuration is incorrect.

The actual wiring of external contacts does not match expectations.

resolvent:

Enter the K-Chief configuration software and check the "trigger logic" parameters of the corresponding channel (usually with "normally open" or "normally closed" options).