1. DESCRIPTION

The C124 Coincidence Buffer is a 24-binary-bit wide, two fold, coincidence module in a CAMAC standard double-width module. The inputs are NIM- standard negative fast logic signals, and the output of the 24 latches is on the CAMAC dataway and on a rear panel connector. The rear panel outputs are MECL. When the module inputs are in coincidence with the external strobe, the 24 latches are set. The bits are gated onto the 24 CAMAC Dataway R lines upon receipt of the proper command from the crate controller. The output of the latches is available immediately at the rear panel. The strobe is a bridging type of input. The bridging inputs of the Strobe signal allow the signal to be reused.

The Strobe signal circuit automatically latches on the trailing edge of the first Strobe signal in order to block any subsequent Strobe signals from activating the Strobe signal circuit until the latches have been reset. The data and strobe latches are reset by the Dataway S2-line Strobe signal and any one of function code F(2), function code F(9), and the Dataway C- and Z-line signals (but not function code F(0)) or by a NIM-standard negative fast logic Reset signal fed from an external source through the front panel Reset connector on this module. The reset input is also of the bridging type.

2. SPECIFICATIONS
 2.1 DATA INPUTS
 In 0 - In 23 LEMO connectors, front panel.
 Circuit Characteristics: 50 Ohm terminated, with <10% reflections for inputs having a 1-nSec rise time; dc-coupled.
 Typical Input: NIM-standard fast logic signals > 2 nSec in width, measured at the half-peak-height point on pulses of -600 mV peak amplitude.
 Maximum Input: +1. 5 V and -3 V.

 2.2 CONTROL INPUTS
Front Panel
Strobe (2)  LEMO connectors.
Circuit Characteristics: Bridging type, with <20% reflections in a 50 Ohm system, if Strobe signal line or lines are terminated or reused in their characteristic impedances; input impedance 2 kOhm; dc-coupled.

Input: Same as Data.
 
Reset: circuit and inputs same as Strobe.
Front panel Reset input signal performs same function as Dataway C- and  Z-line signals.

Rear Panel
Dataway Lines
C and Z: Each will reset the Data and Strobe latches on the leading edge of the Dataway S2-line Strobe signal.
S2: Strobe signal provides timing for resetting of Data and Strobe signal latches.

CAMAC Function Codes

     F(0)  Read Register.

     F(2)  Read and clear register.

     F(9)  Clear register.

     F(25) Set all latches.

2. 3  OUTPUTS (Rear Panel)
Dataway R1-R24 lines: Data outputs; LSB = R1, MSB = R24.
Dataway Q Line: Signal generated by the C124 in response to a valid subaddress (A(O) only), function code, and N-line signal.
Data - rear panel connector (2DB52P).
Outputs are MECL.
The connector is wired to take twisted pair cable.