'''[wiki:GraspSwControllerCmd leds]'''

[[TracNav(GraspContents)]]

||Command:||'''leds'''||
||Contexts:||Network socket, serial console.||
||Function:||Disables or Enables the STARGRASP controller's diagnostic LEDs||
||Required Parameters:||none.||
||Optional Parameters:||on | off||

== About the Diagnostic LEDs ==

The STARGRASP FPGA board has 6 diagnostic LEDs.  5 are in a row on the
top edge of the board, and the 6th is with the fiber for the Ethernet.
The Ethernet light behavior is fairly standard: Solid (green)
indicates a link has been established, and blinks correspond to
packets going in or out.  Note that packets could be any Ethernet
packets, including ARP requests or DHCP requests, so blinks do not
necessarily indicate that IP has been configured.  LED D2 can be used
to determine more about IP addressing and logging.

=== D1 (green) ===
 * Blinks a few times rapidly: Selftests are about to start.
 * OFF: Selftests are in progress, or have failed.
 * ON: Selftests completed successfully.
 * Blinks a few times slowly: Selftest completed, but failed (will stay off after.)

=== D2 (green) ===
 * ON indicates the board has an IP address.  This could either be a static IP or one assigned by DHCP.
 * Blinks: each time a TCP log message is successfully sent (1Hz status update or other message)

=== D3 (red) - OPB Error ===
 * ON after a bus error occurs.

=== D4 (red) - PLB Error ===
 * ON after a bus error occurs.

=== D5 - FPGA Done? ===

Currently, it is not possible to determine if one of the red error
LEDs is lit (or that a bus error has occurred) other than by looking
at the boardset.

=== "leds off" ===

Whether any of the leds are lit or not, it is advisable to issue the
"leds off" command at the start of every exposure to ensure that the
controller is not adding stray light before the shutter opens.  In the
case of D3/D4, these lights will be silently made dark and will not
re-light unless another bus error occurs.  In the case of D1/D2 and
the Ethernet light, those LEDs will continue operating normally once
"leds on" is issued.

If your CCD is configured to use background cleaning, the "leds off"
command also serves as a way to stop cleaning before integration
begins, because any command received by the controller will stop
background cleaning.