See also Serial Link Receiver Specifications
| Signal | In/Out | Used By | Comments |
| SCL_ACK | Out | VME/SCL | In reset |
| SCL_READY | In | VME/SCL | valid trigger/timing info |
| SCL_SYNCERROR | In | VME/SCL | |
| SCL_DATAERROR | In | VME/SCL | |
| CLK_53 | In | VME/SCL | Main clock - always present |
| CLK_7 | In | VME/SCL,GAB,TAB | BC clock - only on valid data |
| CURRENT_TURN[15..0] | In | [gen] | Turn Number - this period |
| CURRENT_BX[7..0] | In | [gen] | Crossing Number - this period |
| FIRST_PERIOD | In | GAB,TAB | 1st period in turn |
| BEAM_PERIOD | In | VME/SCL | Period with beam marker |
| SYNC_GAP | In | GAB | No L1 Accepts Used for sync of signals to TFW |
| COSMIC_GAP | In | Only Cosmic triggers | |
| SPARE_PERIOD | In | ||
| L1_PERIOD | In | VME/SCL | L1 Accept this period |
| L1_ACCEPT | In | GAB,TAB | L1 Accept this geographic section L1_ACCEPT & L1_PERIOD is sent |
| L1_TURN[15..0] | In | [stored] | Turn Number - L1 Accept |
| L1_BX[7..0] | In | [stored] | Crossing Number - L1 Accept |
| L1_QUAL[15..0] | In | GAB | Only CollectStatus bits |
| L2_PERIOD | In | L2 decision this period | |
| L2_ACCEPT | In | L2 Accept this geographic section | |
| L2_REJECT | In | L2 Reject this geographic section | |
| INIT_SECTION | In | GAB,TAB | Initialize |
| L1_BUSY | Out | VME/SCL | Sending data to L2 |
| L2_BUSY | Out | ||
| L1_ERROR | Out | GAB | Request initialization |
| L2_ERROR | Out | ||
| INIT_ACK | Out | VME/SCL | Acknowledge init request |
| SYNC_LOST | Out | VME/SCL | |
| SPARE_STATUS[1..0] | Out | ||
Transmission of the necessary subset of SCL timing and control signals to the TAB is made via the VME/SCL Interface board (VME/SCL) using LVDS protocol with 6 data pairs. A similar cable and connector is used for this transmission as is used for ADF-to-TAB data transmission. The only difference is that three 5-pin rows are used for the VME/SCL data rather than four 5-pin rows for the ADF-to-TAB cables.
The GAB uses as similar set of signals. To be added...
| Pair | Name | Description |
| 1 | clk7 | SCL CLK7 |
| 2 | init | initialize request |
| 3 | turn | SCL FIRST_PERIOD |
| 4 | l1_accept | SCL L1_PERIOD & L1_ACCEPT |
| 5 | pulse | used for L1Cal-internal sync pulse |
| 6 | spare |
Bunch Crossing (BC) numbers corresponding to the BC in which the data was actually produced in the calorimeter are transmitted along with the TT Et's from the ADF. Click here for details. Note: this BC is several (need to specify this exactly) ticks earlier than the BC/TURN currently being sent on the SCL.
BC and TURN numbers are generated in the TABs and GAB from CLK_7 and FIRST_PERIOD signals. They must be synchronized to the BC expected from the ADFs in order to allow data synchronization checks and to correctly mark data in the SYNC_GAPs for use by the TFW and Cal-Track system.
The following algorithms are used to achieve this synchronization.
| BX Counter | 8-bit (1:159) | |
| incremented on: | CLK_7 | |
| reset to | 1 | when BC=160 |
| reset to | BC0(ADF) | by FIRST_PERIOD |
| reset to | 0 | by INIT_SECTION |
| TURN Counter | 16-bit | |
| incremented on: | FIRST_PERIOD + N ticks | |
| reset to | 0 | by INIT_SECTION |
BX and TURN numbers generated for the bunch crossing in question are stored with the L2/L3 data in a fixed depth pipeline. L1_ACCEPT is used to transfer this data to the L2/L3 buffer.
| Bit | Name | HW/Std | Used by L1Cal |
| 00 | L2ForcedWrite | Std | no |
| 01 | L2GlobalNeeded | Std | no |
| 02 | L2MuNeeded | Std | no |
| 03 | L2UnbiasedSample | HW | no |
| 04 | L2EmNeeded | Std | no |
| 05 | L2JetNeeded | Std | no |
| 06 | L2EtMissNeeded | Std | no |
| 07 | CollectStatus | HW | Yes - Collect monitoring data |
| 08 | L2PSNeeded | Std | no |
| 09 | L2TrackNeeded | Std | no |
| 10 | L2ImpactNeeded | Std | no |
| 11 | reserved | HW | |
| 12 | Std | ||
| 13 | Std | ||
| 14 | L2STTNeeded | Std | no |
| 15 | reserved | HW |