All front panel I/O's are LEMO, NIM level. Inputs have 51ohm impedance.
Power requirements: +6V - 0.9A, -6V - 1.9A
General Description
The module passes a copy of an input pulse to the corresponding output with a delay of about 3 nsec. In ``normal" mode, an output appears every N+1 pulses where N is the programmed prescale value for a given channel; note N=0 is a valid setting which produces an output for every input. In this mode, channels 0,1 & 2 can be set from N = 0 to N = 65535 (16 bits), and channel 3 from N = 0 to 16,777,215 (24 bits). In ``fractional" mode an output appears every N/N+1 pulses (N=0 passes nothing). In this mode N max is 255 (8 bits) for all channels. In both modes, an output pulse appears on the first counting cycle. The input to output delay is independent of the prescale value. Individual channels can be enabled and disabled through Camac. An input pulse width of 3 nsec or greater will produce a full height output pulse.
Inhibit input and operation
A front panel global inhibit input is provided which gates off
the outputs and pauses the counters. The module is designed so that
an output pulse will not be truncated by the application of the
inhibit. The inhibit for each channel is latched by the corresponding
input signal. If an input is true, the state of inhibit for that
channel cannot change.
OR output
A double drive output which is the logical "OR" of the four
outputs is also provided. It is available on a pair of LEMO
connectors to facilitate chaining. The "OR" out is coincident with
the individual outputs to within 1 ns.
Camac Operation
The prescale values are written from Camac and stored in
registers. A Camac F9A0 or F11A0 loads the contents of the registers
into the counters. In the absence of F9A0 or F11A0, the counter will
complete its current cycle before taking on a new value. Specific
commands are given at the end of the write-up.
Displays
Two LED digits controlled by a thumbwheel switch are provided to
display the prescale values in hexadecimal. The higher order bits
appear on the upper LED. Thumbwheel positions 0 and 1 display the
divide value for channel 0 from least significant to most significant
byte. Positions 2 and 3 display the value for channel 1,
Positions 4 and 5 channel the value for channel 2,
Positions 6, 7 and 8 display the value for channel 3.
Position 9 is used to display the contents of the control and status
register.
Camac Functions
F0A0..F0A3 - Read the prescale value (16 significant bits) for
channels 0..2 and the lower 16 bits of the prescale value for channel
3.
F0A4 - Read the upper 8 bits of the prescale value for channel 3
F1A0 - Read contents of the control and status register.
F9A0 - Module reset - all channels disabled, all counters loaded with
prescale value, all channels set to ``normal" mode.
F11A0 - Prescalers reset - all counters loaded with prescale value,
but not disabled
F16A0..F16A3 - Write the prescale value (16 significant bits) for
channels 0..2 and the lower 16 bits of the prescale value for channel
3.
F16A4 - Write the upper 8 bits of the prescale value for channel
3
F17A0 - Write control register (8 significant bits).
The function of the bits for the control and status register are
as follows:
0..3 : Enable channels 0..3; 1 - Enabled; 0 - Disabled
4..7 : Select modes for 0..3; 1 - Fractional; 0 -
Normal