Keithley DMM7510 Reference Manual page 235

Section 3: Functions and features Model DMM7510 7½ Digit Graphical Sampling Multimeter Reference Manual
Trigger control modes
You can use the trigger control modes to synchronize instrument operation with the operation of other
instruments. These modes either detect or generate transitions in the state of the line, from high to
low (falling edge) or from low to high (rising edge). The input edge detection setting of the Model
DMM7510 determines which type of transition is detected as an input trigger. Output triggers are
typically generated in the form of a pulse. The type of transition that occurs on the leading edge of the
pulse is determined by an output logic setting. The duration of the pulse is determined by a pulse
width setting.
You can use the trigger control modes with interactive triggering or with the trigger model. For more
information about the trigger modes and triggering, refer to Triggering (on page 3-63).
Open-drain
When you set the instrument to trigger mode and place a line in open-drain mode, the line is
configured to be an open-drain signal with a 100 kΩ pull-up resistor. This makes the line compatible
with other instruments that use open-drain trigger signals, such as other Keithley Instruments
products that only support open-drain for its digital I/O. In this mode, you can use the line to detect
input triggers or generate output triggers, or both. To use this mode successfully, you must carefully
configure the input edge and output logic settings because both of these affect the initial state of the
trigger line. It is recommended that you reset the line before selecting and configuring this mode.
To use the line only as a trigger input:
1. Reset the line.
2. Set the input trigger edge detection type to falling, rising, or either.
The command that sets the detection type automatically sets the line high. This enables the line to
respond to and detect externally generated triggers.
Do not set the output trigger logic type to positive after setting the edge detection type. This sets the
line low, which will prevent the line from operating correctly as a trigger input.
To use the line only as a trigger output:
1. Reset the line.
2. Set the output trigger logic type to negative (falling edge) or positive (rising edge).
When you set the logic type to negative, the instrument automatically sets the line high. Setting the
logic type to positive automatically sets the line low.
Do not set the input trigger edge detection type after setting the positive logic type. This will set the
line high, which will prevent the line from operating correctly as a trigger output.
To use the line as both a trigger input and a trigger output (falling edge triggers only):
1. Reset the line.
2. Set the output trigger logic type to negative (falling edge).
3. Set the input trigger edge detection type to falling, rising, or either.
You can use these settings for triggering applications that use Keithley Instrument products that
feature Trigger Link.
Output
When you place a line in output mode, it is automatically set high or low depending on the output
logic setting. Use the negative logic setting when you want to generate a falling edge trigger. Use the
positive logic setting when you want to generate a rising edge trigger. You cannot detect incoming
triggers on a line configured as a trigger output.
3-52 DMM7510-901-01 Rev. B / May 2015