Charger displays E11, load management with other Heidelberg chargers or building EMS fails, charging current not adjusted.

Safety first: RS‑485 is low‑voltage, but isolate mains before opening the charger to access terminals.

• 1. Verify wiring:
  • Open the charger and locate the RS‑485 / Modbus terminal block.
  • Ensure A/B (or +/–) lines are correctly wired and consistent across all devices in the chain.
  • Check for loose or broken conductors.
• 2. Check termination:
  • Confirm that termination resistors are installed only at the ends of the RS‑485 bus, as per Heidelberg documentation.
• 3. Address and baud rate:
  • Verify each charger has a unique Modbus address.
  • Ensure baud rate, parity, and stop bits match the EMS or master device settings.
• 4. Test communication:
  • If possible, connect a Modbus tester or laptop to the bus and poll the charger.
  • If other devices respond but this charger does not, suspect its RS‑485 interface.
• 5. Replace interface if faulty:
  • If the RS‑485 transceiver is on a plug‑in board, replace that communication interface board.
  • If integrated, main control board replacement may be required.