Spectrum Brands MC.31XX - Manual (Page 62)

62 MC.31xx Manual
General Description Trigger modes and appendant registers
Trigger modes and appendant registers
General Description
The trigger modes of the Spectrum MI, MC and MX A/D boards are very complex and give you the possibility to detect nearly any trigger
event, you can think of.
You can choose between seven external TTL trigger modes and up to 18 internal trigger modes including software and channel trigger, de-
pending on your type of board. Five of the internal trigger modes can be independently set set for each input channel (on A/D boards only)
resulting in a even bigger variety of modes. This chapter is about to explain all of the different trigger modes and setting up the board’s
registers for the desired mode.
Every analog Spectrum board has one dedicated SMB connector mounted in it’s bracket for feeding in an external trigger signal or outputting
a trigger signal of an internal trigger event. Due to the fact that only one connector is available for external trigger I/O, it is not possible to
forward the fed in external trigger signal to another board. If this is however necessary, you need to split up the external trigger signal before.
Software trigger
The software trigger is the easiest way of triggering any Spectrum
board. The acquisition or replay of data will start immediately af-
ter starting the board. The only delay results from the time the
board needs for its setup.
In addition to the softwaretrigger (free run) it is also possible to force a triggerevent by software while the board is waiting for an internal or
external trigger event. Therefore you can use the board command shown in the following table.
Due to the fact that the software trigger is an internal trigger mode, you can optionally enable the external trigger output to generate a high
active trigger signal, which indicates when the data acquisition or replay begins. This can be useful to synchronize external equipment with
your Spectrum board.
Example for setting up the software trigger:
External TTL trigger
Enabling the external trigger input is done, if you choose one of the following external trigger modes. The dedicated register for that operation
is shown below.
Register Value Direction Description
SPC_TRIGGERMODE 40000 r/w Sets the triggermode for the board.
TM_SOFTWARE 0 Sets the trigger mode to software, so that the recording/replay starts immediately.
Register Value Direction Description
SPC_COMMAND 0 r/w Command register of the board.
SPC_FORCETRIGGER 16 Forces a trigger event if the hardware is still waiting for a trigger event. Needs a base board hardware version > 7.x.
Register Value Direction Description
SPC_TRIGGEROUT 40100 r/w Defines the data direction of the external trigger connector.
0 The trigger connector is not used and the line driver is disabled.
1 The trigger connector is used as an output that indicates a detected internal trigger event.
SpcSetParam (hDrv, SPC_TRIGGERMODE, TM_SOFTWARE); // Internal software trigger mode is used
SpcSetParam (hDrv, SPC_TRIGGEROUT , 1 ); // And the trigger output is enabled
Register Value Direction Description
SPC_TRIGGERMODE 40000 r/w
TM_TTLPOS 20000 Sets the trigger mode for external TTL trigger to detect positive edges.
TM_TTLNEG 20010 Sets the trigger mode for external TTL trigger to detect negative edges
TM_TTLBOTH 20030 Sets the trigger mode for external TTL trigger to detect positive and negative edges
TM_TTLHIGH_LP 20001 Sets the trigger mode for external TTL trigger to detect HIGH pulses that are longer than a programmed pulsewidth.
TM_TTLHIGH_SP 20002 Sets the trigger mode for external TTL trigger to detect HIGH pulses that are shorter than a programmed pulsewidth.
TM_TTLLOW_LP 20011 Sets the trigger mode for external TTL trigger to detect LOW pulses that are longer than a programmed pulsewidth.
TM_TTLLOW_SP 20012 Sets the trigger mode for external TTL trigger to detect LOW pulses that are shorter than a programmed pulsewidth.