18
5.4
Gate Menu
OUTPUT
I NPUT
HI GH
LOW
1
2
3
4
GATE MODE:
1
TRI G ENABLE:
OUTPUT
LEVEL TTL:
HI GH
1
2
3
4
Set by user
Set by P400
Figure 6. Gate Menu
To display the Gate menu, press the GATE key. this menu configures the GATE
connector. Turn the spinner knob or use the numeric keypad to select to select one
of the four possible gate modes.
If the gate is configured as an output it will be active (selectably HIGH or LOW) when
triggering is enabled. In burst mode, it will be active during the "pulsing" period of a
burst cycle.
If gate is selected to be an input, an active input level (selectable as TTL HIGH or
LOW) enables triggers.
The four user-selectable gate modes are:
1. The GATE connector is an output, and goes TTL high when triggers are
enabled. It will, for example, pulse high during the active segment of a burst-
mode trigger cycle.
2. Gate is an output as in mode 1, but is active-low.
3. Gate is an input which, if TTL high, enables triggering. Its logic level is
essentially ANDed with any other trigger permissives. The input has a resistive
pullup to +5 volts, so "open" is treated as "high".
4. Gate is an input as in case 3, but is active-low.
The GATE led lights if the gate logic is in its trigger-enable condition, so is always on
in modes 1 and 2. If it is off, the P400 cannot be triggered.
