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52.1 GENERAL DESCRIPTION . . . . . . . . . . . . . . 52-1
52.2 FRONT PANEL . . . . . . . . . . . . . . . . . . 52-1
52.3 FUNCTIONAL DESCRIPTION . . . . . . . . . . . . . 52-2
52.4 POWER SUPPLY REQUIREMENTS . . . . . . . . . . . 52-3
52.5 DRAWING PACKAGE NUMBER . . . . . . . . . . . . . 52-3
52.6 RESPONSIBLE ENGINEER . . . . . . . . . . . . . . 52-4 CHAPTER 52 SIMPLE TIMING BUFFER II (STBII)
52.1 GENERAL DESCRIPTION The STBII performs three functions, one related to CAMAC crate power supply monitoring, and two related to the SLC timing system. LED's on the front panel provide visual indication of CAMAC +/-6V, +/-24V, Y1 (an additional -6V supply) and timing system upper backplane -2V (from the PDUII) supplies being within tolerance. The status of the tolerance of the Y1 and -2V supplies may also be remotely checked through the CAMAC interface, as the Crate Verifier does not monitor these supplies. The STBII fans out to LEMO connectors on the front panel NIM level versions of all 16 channels of timing signals provided by the PDUII to the crate auxiliary upper backplane. The 119 MHz clock with missing pulse fiducial, received from the FIDO by the PDUII and placed on the upper backplane, is also brought out to the front panel. Timing measurements are also performed by the STBII. The time of occurence of a pulse, relative to the fiducial, from any one of the 16 PDUII channels, or from a NIM signal connected to the front panel EXT HALT input, is measured. Edges in the 119 MHz waveform are used to increment a counter, so each count represents an interval of 4.2 nsec. The measurement may be gated by the appropriate occurrence of the PP or YY field received in the broadcast beam codes. When using the STBII to verify PDUII operations, remember that there will be a latency of 7 counts in the measurement, and that the PDUII is programmed in 8.4 nsec increments. That is, if a PDUII channel is programmed to output a pulse at time N, the STBII will measure this pulse as occurring at time (2*N)+7.
52.2 FRONT PANEL o Single Width CAMAC Module o LED's indicating crate +/-24V, +/-6V, Y1 = -6V and Auxiliary Backplane -2V supplies are within tolerance (+/- 5%)
SIMPLE TIMING BUFFER II (STBII) Page 52-2 o 16 LEMO connectors with NIM output signals from CAMAC auxiliary backplane channels 0-F. o 1 LEMO connector with NIM output signal from CAMAC auxiliary backplane 119 MHz. o 1 LEMO connector as NIM input to externally halt the interval timer.
52.3 FUNCTIONAL DESCRIPTION o F(17)A(0) selects the mode of operation of the interval timer. Bits W1-W8 are compared with a selected field in the PP/YY Pattern Input Registers. When a match occurs, the interval timer counter is started when the next fiducial is detected. Bits W9-W13 select which channel is used to stop the interval timer counter. W9-W12 select Ch0-ChF when W13=0. When W13=1, the EXT HALT input is used to halt the interval timer. Bits W14-W16 select a PP or YY field from the PP/YY Pattern Input Registers, for enabling the interval timer, as follows: W16 W15 W14 0 0 0 F19 A8 W1-W8 (YY) 0 0 1 F19 A8 W9-W16 (PP) 0 1 0 F19 A9 W1-W8 (YY) 0 1 1 F19 A9 W9-W16 (PP) 1 0 0 F19 A10 W1-W8 (YY) 1 0 1 F19 A10 W9-W16 (PP) 1 1 0 Undefined (Time slot Info?) 1 1 1 Always generate a match. The interval timer will be started when the next fiducial is detected. Q=1 and X=1 are generated in response to this command. o F(1)A(0) R1-R16 reads back the mode select register (F17 A0 W1-W16). Q=1, X=1. o F(1)A(1) R1-R8 reads back a byte from the PP/YY Pattern Input Registers, as selected by F17 A0 bits W16-W14. Q=1, X=1. o F(9)A(0) resets the module. Q=1, X=1. The module is also reset on Z*S2.
SIMPLE TIMING BUFFER II (STBII) Page 52-3 o F(27)A(0-3) return the following status as Q=1 (Will always return X=1): A(0) - Y1= -6V +/- 5% A(1) - Auxiliary backplane -2V supply = -2V +/- 5% A(2) - Interval measurement data is available A(3) - Match condition - an interval measurement will be started when the next fiducial is detected. o F(19)A(8), A(9), and A(10) are the PP/YY Pattern Input Registers. W1-W16 receive the pipelined beam patterns (PP/YY), for enabling the interval measurements. No Q or X response is generated in response to these commands. o F(0)A(0) R1-R24 reads out the 22-Bit interval timer. The interval timer starts counting when a fiducial is detected from the auxiliary backplane 119 MHz signal, and a match between the PP/YY field of the mode select register and the selected PP/YY Pattern Input Register exists. Counting stops when the selected channel is triggered. The counting clock is derived from edges detected in the 119 MHz waveform. A Q=0 response indicates that an interval measurement has not been made. The interval timer is re-enabled after reading out the interval timer [ F(0)A(0) ], or writing to the mode select register [ F(17)A(0) ]. The interval timer is halted if a stop pulse was not detected by a jumper determining the maximum value of the counter. For 360 Hz. operation, the timer will halt at a count of '10004B'H (corresponding to an interval of 4.4 msec.), and for 180 Hz. operation, the timer will halt at a count of '20004D'H (an interval of 8.8 msec.).
52.4 POWER SUPPLY REQUIREMENTS +24V @ 40mA -24V @ 40mA +6V @ 1.0A -6V @ 2.5A Y1 (aux -6V supply) @ 20mA
52.5 DRAWING PACKAGE NUMBER 233-001
SIMPLE TIMING BUFFER II (STBII) Page 52-4
52.6 RESPONSIBLE ENGINEER E. Linstadt