Issue
The technical documentation for the RP-C-EXT-DALI-M-PD states a guaranteed DALI current limitation of 64 mA. It is unclear whether this limitation applies per DALI port or to the controller as a whole.
Product Line
EcoStruxure Building Operation.
Environment
RP-C-EXT-DALI-M-PD.
Cause
The product documentation lists two current values:
- 250 mA: Theoretical DALI standard maximum bus current.
- 64 mA: Guaranteed current output of the RP-C-EXT-DALI-M-PD module.
This discrepancy has led to confusion regarding whether the 64 mA applies to each port individually or to the total output across all ports.
Resolution
The RP-C-EXT-DALI-M-PD module provides a total guaranteed DALI current of 64 mA, which is shared across all four DALI ports. Key points:
- If only one port is used, it may utilize the entire 64 mA.
- If multiple ports are used, the combined current draw must remain within the 64 mA limit.
- This limitation is enforced by hardware and cannot be exceeded, even with external devices.
- Use of external DALI repeaters with integrated power supplies (e.g., Helvar 405) is not supported due to certification constraints and potential conflicts with the module’s internal power supply.
- The 250 mA figure refers to the DALI standard, not the module’s actual output capability.
As illustrated in the attached diagram, all four DALI ports are powered by a single internal DALI driver, which is the source of the 64 mA limitation.
