Problem

After moving to a new network switch or ethernet infrastructure, JCI Metasys NAE/SNE devices get stuck at "Connecting" status. Field bus devices are erratic or don't respond.

Root Cause

Field bus polarity reversed, duplicate device addresses, or wiring issues caused by the infrastructure change.

Solution

1. For Network Devices (NAE/SNE via Ethernet)

• Check Ethernet cable pinout (most modern switches auto-sense)
• Try swapping the Ethernet cable
• If using unmanaged switch, verify link light is on for that port
• If using managed switch, confirm the port is not disabled or in an isolated VLAN

2. For Field Bus Devices (RS-485 MS/TP)

• Check polarity: A+ and B- are critical—if reversed, devices won't communicate
• Use a multimeter to check voltage between A and B (should show differential ~5V when idle)
• Verify termination resistors are installed at both ends of daisy chain (120 Ω between A and B)

3. Check for Duplicate Device Addresses

• Use Metasys Server or field diagnostics tool to scan for device IDs
• If two devices have the same ID or IP address, they'll conflict
• Reconfigure one device with a unique address and restart

4. Reload Device Configuration

• Sometimes the device firmware needs to be reloaded after a network change
• Power-cycle all devices on the affected segment
• Wait 3–5 minutes for full rediscovery

5. Isolate Problem Segment

• Disconnect part of the network and retry
• Narrow down which segment has the problem
• Focus troubleshooting on the isolated section