With Troubleshooting Guide & Page References from 859749-L - CW-H Multi-Magic - Install and Operation Manual English 

1. Overview

The Multi‑Magic PLC controls the cooler’s fan, pumps, salinity system, communication protocols, sensors, and overall operating logic (PLC overview – p.18).

A PLC replacement may be required when:

• The controller is unresponsive
• Repeated communication faults occur
• Fault Code 1 (PLC–PCBA communication failure) persists
• Physical damage to the display or interface
• Configuration corruption

2. Safety Requirements

Before beginning any PLC service:

1. Isolate power at the mains isolation switch (Electrical Safety – p.14).
2. Use lockout/tagout where required.
3. Ensure water supply is isolated if working near pumps or wet components.

3. Tools & Equipment Required

• Phillips head screwdriver
• Flat blade screwdriver
• Anti‑static wrist strap
• Replacement Multi‑Magic PLC (correct model & voltage)

4. Accessing the PLC

1. Open the electrical enclosure door (see Cooler Control Components – p.16).
2. The PLC is mounted on the enclosure door and includes the LCD screen, navigation keys, USB port, and indicator LEDs (PLC layout – p.18).

5. Removing the Existing PLC

1. Isolate power before disconnecting anything.
2. Disconnect all connectors from the PLC:
   • RS‑485 (Wall / Modbus / BACnet)
   • Sensor inputs (S1–S4)
   • 24VDC power
   • BMS inputs/outputs
3. Label the connectors for reinstallation (careful labelling and identifying connectors at this stage is important).
4. Remove retaining screws and lift out the PLC carefully.

6. Installing the Replacement PLC

1. Fit the new PLC and secure using the mounting screws.
2. Reconnect wiring as labelled:
   • 24VDC supply
   • RS‑485 (observe polarity; see RS‑485 Cable Connections – p.23)
   • Sensors (S1–S4) (Sensor inputs – p.19)
   • BMS terminals (BMS Input Logic – p.24)
3. Ensure the shielded RS‑485 drain is grounded only at one end (RS‑485 Shielding Rules – p.23).

7. Restoring Configuration After PLC Replacement

7.1 Accessing Setup Menu

1. Hold RIGHT button → password screen.
2. Enter 7378.
   (Setup Access – p.26)

7.2 Select Correct Device Type

Navigate SETUP → DEVICE TYPE (see p.13 & p.31):

• CW‑H15
• CW‑H15S
• CW‑H15S Plus
• CW‑H10

Important: Must match the unit rating label.

7.3 Restore Control Method

Set the correct Primary Input Control Method under CONTROL screen – p.18:

• Local
• Wall Controller (RS‑485) (Wall Controller Setup – p.20)
• Modbus (p.21)
• BACnet MS/TP or IP (p.22)
• BMS Low‑Voltage Control (p.24)

7.4 Communication Settings

Wall Controller (p.20)

• Node: 1–15
• Baud Rate: 38400
• Parity: NULL
• Power‑cycle cooler after saving.

Modbus (p.21)

• Node: 1–99
• Baud/Parity must match supervisor.

BACnet (p.22)

• MS/TP: Device ID (1–9999), MAC, Baud, Parity
• IP: IP Address, Gateway, Subnet Mask, Port (47808 default)
• Power‑cycle after changes.

7.5 Cooler Settings

Under SETUP → SETTINGS (p.26) restore:

• Pre‑Wet
• Salinity Drain Set Point
• Fan Start Delay
• Fill Delay
• BMS Lock Speed
• Sensor Units (Metric/Imperial)
• Date & Time (important for fault & drain history – p.31)

8. Commissioning After PLC Replacement

8.1 Component Testing (Service → Test Menu)

Use the SERVICE → TEST MENU on the PLC (see p.31 & p.37):

• Inlet Solenoid
• Drain Valve
• Indirect Pump
• Direct Pump (Supercool only)
• Fan (Speeds 1–10)

8.2 Water Management System Verification

Checklist from p.31:

• Tank fills until Low Probe → detected
• Tank fills until High Probe → detected
• Salinity reading present (>100 µS/cm)
• Pumps activate in correct sequence

If probes misread, see Probe Maintenance – p.39.

8.3 Airflow / Pressure Balancing

Refer to Air Flow Balancing – p.32:

• Run cooler in LOCAL → IEC, Speed 10 for 5 minutes
• Measure pressure at the transition test port
• Adjust transition damper to target plenum pressure:
  • CW-H10: 200 Pa
  • CW-H15: 175 Pa
  • CW‑H15S: 175 Pa
  • CW‑H15S Plus: 210 Pa

9. Troubleshooting – PLC Replacement Issues

9.1 PLC Not Powering On

Possible Causes

• No mains supply to enclosure
• Faulty 24VDC supply (p.14)

Actions

• Check isolation switch
• Verify 24VDC at PLC input

9.2 Wall Controller Not Communicating

Relevant Pages: p.20 (Wall), p.23 (RS‑485 rules), p.29 (Fault Code 16)

Possible Causes

• Incorrect primary control method
• Missing Modbus terminator
• RS‑485 polarity reversed
• Incorrect node address

Actions

• Set CONTROL → WALL
• Check 120Ω terminator at first & last device (p.23)
• Verify A/B wiring
• Confirm node 1–15

9.3 Fault Code 1 – PLC ↔ PCBA Communication Failure

Reference: p.29

Likely Causes

• Loose PCBA harness
• PCBA failure
• PLC failure

Fix

• Check PCBA status LEDs
• Reseat connectors
• Replace PCBA if PLC is new

9.4 Fault Code 7 – Supply Motor Error

Reference: p.29

Causes

• Loose motor cable
• VSD motor error
• Motor fault

Fix

• Check motor power & comms
• Check motor status via MONITOR screen – p.19

9.5 Inadequate Cooling

Reference: Troubleshooting – p.43

Causes

• Running in VENT mode
• DEC not enabled (Supercool)
• Low plenum pressure
• Dirty filters/cores

Fix

• Enable IEC or DEC
• Confirm DEVICE TYPE
• Rebalance airflow (p.32)
• Clean filters (p.40)

9.6 Water System Issues

Causes

• Blocked solenoid strainer (p.38)
• Blocked drain
• Faulty probe (p.39)

Fix

• Clean solenoid mesh
• Clean drain
• Verify probe resistance (<5 Ω)