In alternating current, the zero-crossing is the instantaneous point at which there is no voltage present. In a sine wave or other simple waveform, this normally occurs twice during each cycle. Our system operates or changes state on zero-crossing.
When this error is displayed on the Synergy controller, the controller is informing us that a function was performed when there was voltage. The sine wave was not Zero. To remove the error notation, the controller must be reset with a power-cycle. Switch the on/off switch located to the right of the controller to off. Pull the controller out for 10 seconds and replace it. Turn the switch to on. The controller will initialize the system and the error should clear.