Chapter 5. Operations52 PACSystems* RX3i PROFINET IO-Scanner User Manual GFK-2737F5.1 Power-upWhen power is applied to the PNS module, it loads a firmware image. During the power-up process, themodule runs diagnostics and initializes its hardware components.After completing power-up sequence, the OK LED changes from being off to solid on green. If a fatal erroroccurs during power-up, the amber OK LED blinks a unique pattern indicating the nature of the failure.If the module encounters a hardware failure, invalid firmware image, or the power-up diagnostics fail, themodule will not become operational or may enter firmware update mode. Cycling power to the modulemay restore operation. Refer to Section 6.3, Fatal Error Handling for more details.Non-volatile settings such as the PROFINET Device Name, Ethernet network configuration, and EthernetPort disable settings are activated before a PROFINET connection is allowed.