Smart charging is one of the most powerful and most complex parts of OCPP. It is the mechanism by which a CSMS controls how much power each charging station draws — essential for grid management, demand response, and energy cost optimization. For CSMS developers, testing smart charging requires a simulator that actually enforces profiles and reports back correctly.
What a charging profile is
A charging profile is a power schedule sent from the CSMS to the station via SetChargingProfile. It tells the charger how much power (in watts or amps) it is allowed to deliver over time. The station is expected to enforce the limits in real time and report compliant power values in MeterValues.
A profile contains one or more schedule periods, each with a start offset in seconds from the start of the schedule and a power or current limit. A simple profile might allow full power for 30 minutes, then drop to half power for the next hour, then return to no limit.
Profile purposes
OCPP 1.6 defines three charging profile purposes:
- TxProfile — applies to the currently active transaction on a specific connector. Overrides other profiles for the duration of that transaction.
- TxDefaultProfile — the default profile applied to any new transaction on a connector. Useful for setting a consistent limit without knowing the transaction ID in advance.
- ChargePointMaxProfile — sets an absolute power ceiling for the entire charging station, regardless of what individual connectors are doing. Used for site-level demand management.
Stack levels
Multiple profiles can coexist on the same connector. Stack levels resolve conflicts: a profile with a higher stack level takes precedence over one with a lower level. This allows a CSMS to set a baseline TxDefaultProfile at stack level 0 and override it dynamically at stack level 1 for a demand response event — without clearing the baseline configuration.
Testing smart charging
Testing SetChargingProfile with real hardware typically requires a controllable power load and energy measurement equipment. Most development teams do not have this setup. The result is that smart charging logic — including profile conflicts, expiry handling, and stack level resolution — often goes undertested until production incidents expose it.
SimIt accepts SetChargingProfile commands, stores the full profile stack, and applies the active limit to reported MeterValues power readings. Your CSMS can verify that the profile was received, applied, and reflected in subsequent meter data — without any physical equipment.
Test smart charging scenarios free with SimIt.