Protocols | STT | STSX L3

Media: fiber optic, GLINK
Record Length: variable!

19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
VRB START Header Length #Dwords MSb #LVDS Links
  Hdr Fmt Obj Fmt #Dwords LSb
  Tick Data Type
  Turn
  Link Status word 1
  Link Status word 0
  Input Link Data Block
(varible length)
  Data Type Tick
  Vertical Parity
  Pad Frame(s)
VRB END  

Field Definitions

note: empty cells will contain zeros

VRB START = "0101"

Header Length = 0x03

#Dwords MSb = number of data words (upper nibble) = 0

#LVDS Links = 9 or 10, depends on STSX board position

Hdr Fmt = Header Format, "010"

Obj Fmt = Object format, "00001"

#Dwords LSb = number of data words (lower byte) = variable

Tick = The accelerator bunch crossing number

Data Type = 0x06

Turn = The accelerator turn (revolution) number

Link Status word 1 = 

   [15:14] "00"
   [13:4]  Parity error, input link9:link0
   [3:0]   Tick/Turn error, input link9:link6

Link Status word 0 = 

   [15:10]  Tick/Turn error, input link5:link0
   [9:0]    Link error, input link9:link0

The Input Link Data Block contains 9 (or 10) records from the STOV and DFEA boards.
The first two records are always STOV records. Note that each of these records are variable length,
so careful parsing of the header frames is necessary to properly unpack everything. 

  "00000000000"+link0 frame1 bits[20:16]
  link0 frame1 bits[15:0]
  "00000000000"+link0 frame2 bits[20:16]
  link0 frame2 bits[15:0]
  ...

Vertical Parity is calculated over the L3 record, not including pad frames

Pad Frame(s) = Pad frames are inserted to insure that the total record length is a multiple of 8 frames. This requirement is imposed by the VRB hardware.

VRB END = "1010"

General Information

The STSX default operating mode is to concatenate the L2 and L3 records and send this new large record out on the L3 fiber. The pad frames in each record are not modified. The VRB END marker on the L2 record is zeroed out, as is the VRB START marker on the L3 record.

The STSX boards can also be placed in a mode where they send the just the L2, or L3 record out on the L3 fiber.

Revision History

3 November 2005: created JTO

2 December 2005: removed references to firmware major/minor fields, added link status words. JTO

3 January 2006: added parity links

jamieson@fnal.gov
Last modified: Tue Jan 3 12:33:08 2006