Spectrum M2p.59 Series, Руководство по оборудованию, Страница: 103 / 190

Trigger modes and appendant registers Main analog external trigger (Ext0)
(c) Spectrum Instrumentation GmbH 103
Trigger Mode
Please find the main external (analog) trigger input modes below. A detailed description of the modes follows in the next chapters..
For all external edge and level trigger modes, the OR mask must contain the corresponding input, as the following table shows:
Trigger Input Termination
The external trigger input is a high impedance input with 5 kOhm termination against GND. It is possible to program a 50 Ohm termination
by software to terminate fast trigger signals correctly. If you enable the termination, please make sure, that your trigger source is capable to
deliver the needed current. Please check carefully whether the source is able to fulfill the trigger input specification given in the technical data
section.
Please note that the signal levels will drop by 50% if using the 50 Ohm termination and your source also has 50 Ohm output impedance
(both terminatiors will then work as a 1:2 divider). In that case it will be necessary to reprogram the trigger levels to match the new signal
levels. In case of problems receiving a trigger please check the signal level of your source while connected to the terminated input.
Trigger level
All of the external (analog) trigger modes listed above require a trigger level to be set (except SPC_TM_NONE of course). The meaning of
the trigger levels is depending on the selected mode and can be found in the detailed trigger mode description that follows.
Trigger level for the external (analog) trigger is to be programmed in mV:
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:.
Table 63: Spectrum API: external trigger mode registers and available settings therefore
Register Value Direction Description
SPC_TRIG_EXT0_AVAILMODES 40500 read Bitmask showing all available trigger modes for external 0 (Ext0) = main analog trigger input
SPC_TRIG_EXT0_MODE 40510 read/write Defines the external trigger mode for the external MMCX connector trigger input. The trigger need to
be added to either OR or AND mask input to be activated.
SPC_TM_NONE 00000000h Channel is not used for trigger detection. This is as with the trigger masks another possibility for disabling channels.
SPC_TM_POS 00000001h Trigger detection for positive edges (crossing level 0 from below to above)
SPC_TM_NEG 00000002h Trigger detection for negative edges (crossing level 0 from above to below)
SPC_TM_BOTH 00000004h Trigger detection for positive and negative edges (any crossing of level 0)
SPC_TM_HIGH 00000008h Trigger detection for HIGH levels (signal above level 0)
SPC_TM_LOW 00000010h Trigger detection for LOW levels (signal below level 0)
SPC_TM_POS | SPC_TM_P -
W_GREATER
4000001h Sets the trigger mode for external trigger to detect HIGH pulses that are longer than a programmed pulsewidth.
SPC_TM_POS | SPC_TM_P -
W_SMALLER
2000001h Sets the trigger mode for external trigger to detect HIGH pulses that are shorter than a programmed pulsewidth.
SPC_TM_NEG | SPC_TM_P -
W_GREATER
4000002h Sets the trigger mode for external trigger to detect LOW pulses that are longer than a programmed pulsewidth.
SPC_TM_NEG | SPC_TM_P -
W_SMALLER
2000002h Sets the trigger mode for external trigger to detect LOW pulses that are shorter than a programmed pulsewidth.
Table 64: Spectrum API: trigger or mask and setup for external trigger
Register Value Direction Description
SPC_TRIG_ORMASK 40410 read/write Defines the OR mask for the different trigger sources.
SPC_TMASK_EXT1 4h Enable secondary external trigger input for the OR mask
Register Value Direction Description
SPC_TRIG_TERM 40110 read/write A „1“ sets the 50 Ohm termination for external trigger signals. A „0“ sets the high impedance termi -
nation
Table 65: Spectrum API: software registers for external trigger levels
Register Value Direction Description Range
SPC_TRIG_EXT_AVAIL0_MIN 42340 read returns the minimum trigger level to be programmed in mV
SPC_TRIG_EXT_AVAIL0_MAX 42341 read returns the maximum trigger level to be programmed in mV
SPC_TRIG_EXT_AVAIL0_STEP 42342 read returns the step size of trigger level to be programmed in mV
SPC_TRIG_EXT0_LEVEL0 42320 read/write Trigger level 0 for external trigger Ext0 -5000 mV to +5000 mV
Table 66: Spectrum API: software registers to program external trigger
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.