SCSI Enclosure Services (SES) devices contains a number of elements, each of which is defined by a one byte SCSI element code. There are many different element codes defined to cover various devices as shown in the list below. List of SES element codes 00h - unspecified 01h - device - disk-drive or other SCSI device 02h - power-supply 03h - cooling 04h - temperature-sensor 05h - door lock 06h - audible alarm 07h - enclosure services controller electronics 08h - SCC controller electronics 09h - nonvolatile cache 0Ah - invalid operation reason - used to determine why an ESI device has failed to complete a command 0Bh - UPS 0Ch - display 0Dh - keypad 0Eh - enclosure 0Fh - SCSI port/transceiver 10h - language 11h - communication port 12h - voltage sensor 13h - current sensor 14h - SCSI target port 15h - SCSI initiator port 16h - simple subenclosure 17h - array device 18h - SAS expander 19h - SAS connector 1Ah-7Fh - reserved 80h-FFh - vendor-specific How SES elements are used The SCSI initiator communicates with an SES device using two SCSI commands, Send Diagnostic and Receive Diagnostic Results. The most common SES elements are power-supply, cooling-fan, temperature-sensor and UPS. The SCSI command protocols assume that there may be more than one of each device type so they must each be given an 8-bit address. When the SES controller is interrogated for the status of an SES element, the response includes a 4-bit status code. The most common element status codes are: 1h=OK, 2h=critical, 3h=warning, 5h=not installed. See the SES article for a more detailed description. Status codes When a SCSI SES controller is interrogated for the status of a SES element, the response includes a 4-bit SCSI element status code. The list of valid codes is: 0h - unsupported - status detection is not implemented for this element 1h - OK - element is installed and no error conditions are known 2h - critical - critical condition is detected 3h - noncritical (warning) - noncritical condition is detected 4h - unrecoverable - unrecoverable condition is detected 5h - not installed - this element is not installed in the enclosure 6h - unknown - sensor has failed or element status is not available 7h - not available - element installed, no known errors, but the element has not been set into operation 8h-Fh - reserved References