ESS Series User’s Manual89The ESS3124D-JR rear panel is shown as In Figure 5-13.Figure 5-13You can refer to the following sheet for detailed information of the rear panel.SN Port Function1 Fan It is for case ventilation.2 Power port Connect to AC power supplying source.3 Main control module It is about all kinds of ports and indictor lightintroduction. Please refer to the following sheet.You can refer to the following sheet for detailed information of main control module.Port/IndicatorLightFunctionIN port indicatorlightThe Link light is on when the IN port has connected to the host or the upper-level disk array enclosure.The Access light is on when the host is accessing the HDD of the disk arrayenclosure.IN port Connect IN port to the host (such as ESS5024D-R) or the OUT port of theupper-level disk array enclosure. Access the HDD of the disk array enclosurevia the IN port.COM Access system via COM. It is mainly for device debug.Indicator light The RUN light is on when device has booted up and is working.M/S is main control indicator light. The light is on when system is workingproperly. The light is off when the system is abnormal.The ERR light is on when system is malfunction. The ERR light is off whensystem is working properly.The SPD light is on when the HDD access speed is abnormal. The SPD lightis off when HDD access speed is normal.OUT port Connect OUT port to the sub-level disk array enclosure to realize cascadeconnection.OUT portindicator lightThe Link light is on when OUT port has connected a sub-level device.5.7 ESS3148S-J/ ESS3148S-JR