Trigger modes and appendant registers | Channel Trigger |
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If you want to set up a four channel board to detect a triggerevent on either a positive edge on channel1 or a negative edge on channel3 you would have to set up your board as the following example shows.
SpcSetParam (hDrv, | SPC_TRIGGERMODE , | TM_CHOR ); | // Enable channel OR trigger mode |
SpcSetParam (hDrv, | SPC_TRIGGERMODE0, | TM_CHXOFF); | // Disable channel0 concerning trigger detection |
SpcSetParam (hDrv, SPC_TRIGGERMODE1, TM_CHXPOS); | // Set triggermode of channel1 to positive edge trigger | ||
SpcSetParam (hDrv, | SPC_TRIGGERMODE2, | TM_CHXOFF); | // Disable channel2 concerning trigger detection |
SpcSetParam (hDrv, SPC_TRIGGERMODE3, TM_CHXNEG); | // Set triggermode of channel3 to positive edge trigger | ||
SpcSetParam (hDrv, SPC_TRIGGERMODE4, | TM_CHXOFF ); | // Disable channel4 concerning trigger detection | |
SpcSetParam (hDrv, SPC_TRIGGERMODE5, | TM_CHXOFF ); | // Disable channel5 concerning trigger detection | |
SpcSetParam (hDrv, SPC_TRIGGERMODE6, | TM_CHXOFF ); | // Disable channel6 concerning trigger detection | |
SpcSetParam (hDrv, SPC_TRIGGERMODE7, | TM_CHXOFF ); | // Disable channel7 concerning trigger detection |
Triggerlevel
All of the channel trigger modes listed above require at least one triggerlevel to be set (except TM_CHXOFF of course). Some like the window trigger require even two levels (upper and lower level) to be set. Before explaining the different channel trigger modes, it is necessary to explain the board’s series specific range of triggerlevels.
After the data has been sampled, the upper N data bits are compared with the N bits of the trigger levels. The amount of bits, the trigger levels are represented with depends on the board’s series. The following table shows the level registers and the possible values they can be set to for your specific board.
8 bit resolution for the trigger levels:
Register | Value | Direction | Description | Range |
SPC_HIGHLEVEL0 | 42000 | r/w | Defines the upper level (triggerlevel) for channel 0 | |
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SPC_HIGHLEVEL1 | 42001 | r/w | Defines the upper level (triggerlevel) for channel 1 | |
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SPC_HIGHLEVEL2 | 42002 | r/w | Defines the upper level (triggerlevel) for channel 2 | |
SPC_HIGHLEVEL3 | 42003 | r/w | Defines the upper level (triggerlevel) for channel 3 | |
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SPC_HIGHLEVEL4 | 42004 | r/w | Defines the upper level (triggerlevel) for channel 4 | |
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SPC_HIGHLEVEL5 | 42005 | r/w | Defines the upper level (triggerlevel) for channel 5 | |
SPC_HIGHLEVEL6 | 42006 | r/w | Defines the upper level (triggerlevel) for channel 6 | |
SPC_HIGHLEVEL7 | 42007 | r/w | Defines the upper level (triggerlevel) for channel 7 | |
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SPC_LOWLEVEL0 | 42100 | r/w | Defines the lower level (triggerlevel) for channel 0 | |
SPC_LOWLEVEL1 | 42101 | r/w | Defines the lower level (triggerlevel) for channel 1 | |
SPC_LOWLEVEL2 | 42102 | r/w | Defines the lower level (triggerlevel) for channel 2 | |
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SPC_LOWLEVEL3 | 42103 | r/w | Defines the lower level (triggerlevel) for channel 3 | |
SPC_LOWLEVEL4 | 42104 | r/w | Defines the lower level (triggerlevel) for channel 4 | |
SPC_LOWLEVEL5 | 42105 | r/w | Defines the lower level (triggerlevel) for channel 5 | |
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SPC_LOWLEVEL6 | 42106 | r/w | Defines the lower level (triggerlevel) for channel 6 | |
SPC_LOWLEVEL7 | 42107 | r/w | Defines the lower level (triggerlevel) for channel 7 |
In the above table the values for the triggerlevels represent the digital values for the corresponding data width N of the triggerlevels. If for example the triggerlevels are represented by 8 bit, the bipolar range would be
As the triggerlevels are compared to the digitized data, the triggerlevels depend on the channels input range. For every input range available to your board there is a corresponding range of triggerlevels. On the different input ranges the possible stepsize for the triggerlevels differs as well as the maximum and minimum values. The following table, gives you the absolute triggerlevels for your specific board’s series.
(c) Spectrum GmbH | 67 |