The EST3 is showing a network communication trouble — how do I determine which segment or node is causing it?

To determine the failed segment, identify where the network has split into independent sub-networks by checking which panels are still communicating. The fault is located between the last communicating node of the first sub-network and the first node of the second (Page 262) [1].

1. Check CPU LEDs RX2/TX2 and RX3/TX3; they should flicker continuously during normal operation (Page 260) [1].

2. Identify the break by finding the two cabinets where communication stops (Page 262) [1].

3. Inspect wiring for reversed polarity, crossed A/B loops, or improper termination at those nodes (Page 185) [1].

4. Ensure the 3-RS485 card or network option card is firmly seated in the CPU (Page 262) [1].