2.1 General

2.1.1 The module shall be a single width CAMAC module.

2.1.2 There shall be at least four (4) scaler channels in the module.

2.1.3 The module shall comply with the general standards for CAMAC mod ules as stated in Appendix B.

2.1.4 Each scaler shall be a binary scaler with a full scale capacity of 2^24 - 1.

2.2 Scaler Input Characteristics

2.2.1 There shall be one (1) NIM FAST scaler input per channel.

2.2.2 The scaler shall count at least 0 to 100 MHz C.W. and have a double pulse resolution not exceeding 10 nsec.

2.2.3 The scaler shall count any NIM FAST pulse whose width is equal to or greater than 3.5 nsec.

2.2.4 The scaler must not increment more than once for any NIM FAST pulse.

2.3 Inhibit Input Characteristics

2.3.1 There shall be 1 bridged NIM FAST input common to all scaler channels for inhibiting the scalers.

2.3.2 Logic "0" shall enable, logic "1" shall inhibit.

2.3.3 The inhibit signal shall not cause any scaler to increment under any circumstances.

2.3.4 The module response time for an inhibit input shall not exceed 10 nsec.

2.4 Inhibit Switch

2.4.1 A locking toggle switch shall permit the following. operation:

Position 1. Scalers can be inhibited by either a CAMAC I command OR a front panel inhibit input.

Position 2. Scalers can be inhibited only by the front panel inhibit input.

2.5 Reset Input

2.5.1 A bridged TTL (CAMAC unterminated) input shall allow electrical resetting of all scalers. A CAMAC logic "1" (low) shall reset.

2.5.2 There shall be no carry overflow pulse as a result of reset operation.

2.6 Front Panel Display

2.6.1 A front panel LED shall indicate whenever the module is addressed by the station address line.

2.6.2 A front panel LED shall indicate whenever the module is not inhibited (i.e. enabled).

2.7 Carry Overflow-Rear Panel

2.7.1 There shall be 1 carry overflow pulse output (NIM FAST) for each scaler.

2.7.2 The output shall be on the rear panel, and may be either a LEMO connector or a printed circuit card edge output.

2.7.3 An internal jumper shall allow selecting an over- flow at either 2^16 or 2^24

2.7.4 The carry output pulse shall be at least 50 nsec wide, but not more than usec wide, and shall have rise and fall times not exceeding 10 nsec.

2.8 Unaddressed Dataway Operations

2.8.1 A Z-S2 or a C-S2 shall cause all scalers to reset. An I shall inhibit all scalers from incrementing (see paragraph 2.4).

2.8.2 No unaddressed dataway command shall cause any scaler to increment, nor cause a carry overflow to be generated.

2.9 Addressed Dataway Commands

2.9.1 The following operations shall be available,and shall provide an X response:

 N-F(0) - A (x)   0 =< x =< 3  Read scaler x

 N-F(2) - A (x)   0 =< x <= 3  Read and clear scaler x

 N-F(9) - A (x)   0 =< x <= 3  Clear scaler x

 N-F(25) -A (x)-S2  0 =< X <= 3  Increment all scalers
        by 1.

2.9.3 (optional) There shall be a multiple-source LAM structure for indicating scaler overflows. An N-F(l) - A(12) command shall allow reading the LAM status registers onto the Dataway (see TID 25875, paragraph 5.4.1.2).