8
3.3 INDICATORS
Two LED indicators are provided o n the front panel. One indicates
the MODID status and the other indicates the board status.
MODID: This front panel LED illuminates whenever the host
processor applies the MODID signal to the slot the
module is occupying.
RUN: This front panel LED illuminates when the modules
is activ ely outpu tting p ulses.
3.4 CONNECTORS
3.4.1 Front Panel Co nnectors
Three BNC type connectors are provided for the pulse output, trigger
output, and trigger input as shown in Figure 4. Their functions are as
follows:
TRIG IN This TTL level Trigger Input signal initiates the pulse
cycles when Free Running Mode bit (FRE) in the Pulse Control
Register is set t o zero. If the Trigger Mode bit (TMD) is zer o the
rising edge of this signal starts one pulse cycle (single or double pulse). If the TMD bit is set
to one, the TRIG IN signal acts as a gate. This gate allows the pulse cycle to repeat
continuously while the gate is high. When the gate is lowered, the current pulse cycle
completes, and the pulse output stops.
TRIG OUT This TTL level Trigger Output signal indicates the beginning of a pulse cycle. It
occurs 50-75ns after the RUN bit is set or the t rigger input (TRIG IN) signal goes high. In
single or double pulse mode, the output pulse (PULSE OUT) will start appr oximately 25ns
after trigger out. In delayed pulse mode, the output pulse will start the pro grammed time after
trigger out + approximately 25ns. The width of trigger out is equal to the pulse width range
selected (i.e., 2 5ns, 100ns, 1s, et c.). When in free running mode a trigger output signal will
occur at the beginning of every cycle.
PULSE OUT The amplified pulse cycles are available at this connector. The output
impedance o f t his signal in jumper selec table betwe en 2 or 50 Ohms (see figur e 3 ). T he
output amplitude, cycle period, pulse width, and other pulse and trigger characteristics are
register programmable.
3.4.2 Rear Connectors
The P1 and P2 connectors are configured in accordance with the VXI specification. (See
Appendix B)
VX462B
RUN
MODID
PULSE
TRIG
TRIG
VXI
bus
OUT
OUT
IN
Figure 4. Front Panel