The EY Slow controls issue escalated overnight, DEV5 now has no communication with EY.
The link deteriorated over the course of 5 hours, starting at 23:24 Sat 19sep2026 and was completely lost by 04:23 Sun 20sep2026.
Trending the slave_count_actual for DEV5 shows it erratically drops from 127 to 1 over this time period.
WP 13633
The EK1501-0010 Coupler in the EY End Link Chassis was replaced.
Started troubleshooting in the CER. Found the CU1521 media converter for EY had all link lights OFF. The EY fiber was removed and the EX fiber connected. Link lights powered on. This indicated issue at EY.
Removed the cover from the End Link Slow Controls Chassis and found link and power lights OFF. EtherCAT coupler EK1501-0010 was replaced. The CER D1700494 had to be power cycled for terminals to begin communicating.
End Link Chassis Serial Number: S1103494
D. Barker, F. Clara, R. McCarthy, P. Thomas