Spectrum M2p.59 Series, Hardware Manual, Page: 138 / 190

138 (c) Spectrum Instrumentation GmbH
Trigger Mode Gated Sampling
Trigger
Detailed description of the external analog trigger modes
For all external analog trigger modes shown below, either the OR mask or the AND must contain the external trigger to activate the external
input as trigger source:.
The following pages explain the available modes in detail. All modes that only require one single trigger level are available for both external
trigger inputs. All modes that require two trigger levels are only available for the main external trigger input (Ext0).
Trigger on positive edge
The trigger input is continuously sampled with the selected
sample rate. If the programmed trigger level is crossed by
the trigger signal from lower values to higher values (rising
edge) then the gate starts.
When the signal crosses the programmed trigger level from
higher values to lower values (falling edge) then the gate
will stop.
As this mode is purely edge-triggered, the high level at the
cards start time does not trigger the board.
Trigger on negative edge
The trigger input is continuously sampled with the selected
sample rate. If the programmed trigger level is crossed by
the trigger signal from higher values to lower values (falling
edge) then the gate starts.
When the signal crosses the programmed trigger from low -
er values to higher values (rising edge) then the gate will
stop.
As this mode is purely edge-triggered, the low level at the
cards start time does not trigger the board.
High level trigger
The external input is continuously sampled with the selected
sample rate. If the signal is equal or higher than the pro -
grammed trigger level the gate starts.
When the signal is lower than the programmed trigger level
the gate will stop.
As this mode is level-triggered, the high level at the cards start
time does trigger the board.
Table 84: Spectrum API: external analog trigger registers
Register Value Direction Description
SPC_TRIG_ORMASK 40410 read/write Defines the events included within the trigger OR mask of the card.
SPC_TRIG_ANDMASK 40430 read/write Defines the events included within the trigger AND mask of the card.
SPC_TMASK_EXT0 2h Enables the main external (analog) trigger 0 for the mask.
Register Value Direction set to Value
SPC_TRIG_EXT0_MODE 40510 read/write SPC_TM_POS 1h
SPC_TRIG_EXT0_LEVEL0 42320 read/write Set it to the desired trigger level in mV. mV
Register Value Direction set to Value
SPC_TRIG_EXT0_MODE 40510 read/write SPC_TM_NEG 2h
SPC_TRIG_EXT0_LEVEL0 42320 read/write Set it to the desired trigger level in mV. mV