SAS ELA Hardware Connections

Hardware Explanation

The SAS ELA is the EasyLinx Adapter that is placed behind the slot. It's a computer (Raspberry Pi) with a shield board connected to it. 

The ELA in its case is illustrated in the following image:

Outside of its case, it can be seen that there is a color coded pattern in the wires (screwed to the blue terminal block) right next to the power switch. The order of wires is important and must be used as shown in the picture. 

Hardware Troubleshoot

Behind the blue terminal block, there are six LEDs in the following order:

1. Rx (Yellow)
2. Tx (Blue)
3. Server (white)
4. TTL - Rx
5. 232 - Rx
6. Firmware (Green)

• The most important ones to diagnose a scenario are the first three LEDs. The LED  6 should be on to confirm that the ELA has power. If it is not on, it is a sign that the ELA has no power. The LEDs 4 and 5 are not relevant to the scenario. 
• The third white LED labeled "Server" will display a flashing pattern that indicates specific diagnostics, depending on how many times it flashes:

  2 flashes - "Host Connection Down"
  3 flashes - "Slot Link Down"
  4 flashes - "Slot not receiving ELA commands. Data connector reversed (wrong polarity) or Tx line (blue) not connected"
  5 flashes - "Not Promoted"
  6 flashes - "Validation Not Set"
  7 flashes - "Low Wireless Signal"

  Flashes are followed by a long pause.

• When a machine is up and communicating with the system the first two LEDs should be flashing blue and yellow lights and a pattern that they seem to follow each other.
  • If only the first LED is blinking (yellow) it is a sign that the ELA is not booting - important to highlight that this behavior must be noted after two minutes (time to ELA regularly boot). In this case, a power cycle shall be done first. If the scenario persists, two paths can be followed:
    • the customer should be asked to swap the SD card from the raspberry board with another one that is certainly good;
    • the whole ELA must be swapped (most used because the customers usually don't have tech knowledge). 
  • With this, it can be discovered that the ELA itself was the root cause of the scenario.  
  • If only the second LED is blinking (blue) it indicates that there is an issue with the communication of the slot and the yellow status on the slot management should be seen for the slot. This is a situation where the communication cable and the terminals of the com connectors must be reviewed and redone - more info regarding the topology of the jumpers on the Communication Connectors for each slot Brand section.
• If the LEDs 1 and 2 are blinking, but they are in an irregular flashing pattern and it's on the LED of the firmware, it's a sign that the polarity of the comm cable is inverted - check the white LED that may blink four times.