How are stimulator trigger signals handed by BioSemi hard and software ?
 

The ActiveTwo USB receiver has 16 independent trigger inputs and 16 independent trigger outputs (TTL level, 37-pole sub-d connector on the frontpanel of the receiver). The input trigger signals are mixed with the digital data coming from the AD-box. The input trigger signals are saved in an extra channel (the status channel), with the same sample rate as the electrode channels. So, the timing of the trigger inputs is accurate to the time period of a sample. The trigger output signals can be controlled with an extra independent LabVIEW thread integrated in the BioSemi acquisition software. Because the trigger inputs are located at the receiver, the trigger inputs and connected trigger equipment remains completely galvanically isolated from the front-end and the subject, this ensures that the trigger equipment can not cause any additional interference and provides optimal subject safety.
Because our acquisition software saves the electrode signals and trigger signals in .BDF (BioSemi Data Format), off-line ERP analysis can be performed with one of the many available third-party software package that are compatible with the .BDF format. Manufacturers who support the .BDF format automatically read our digital trigger format. No old fashioned setting of analog trigger levels etc is needed.

ActiView always automatically saves all 16 Triggers in an extra channel. It is not possible to NOT save the triggers. (to prevent any user mistake)

In the tables below you can find the connections of the trigger input and a description of the Status channel.

All the Trigger inputs have internal 10 kOhm pull-ups, thus the triggers are normally "on".
 
25 pin female sub-D (PCI interface)
37 pin female sub-D (USB interface)
Status channel information
Pin01
Trigger input 1
Pin02
Trigger input 2
Pin03
Trigger input 3
Pin04
Trigger input 4
Pin05
Trigger input 5
Pin06
Trigger input 6
Pin07
Trigger input 7
Pin08
Trigger input 8
Pin09
Trigger input 9
Pin10 Trigger input 10
Pin11 Trigger input 11
Pin12 Trigger input 12
Pin13 Trigger input 13
Pin14 Trigger input 14
Pin15 Trigger input 15
Pin16 Trigger input 16
Pin17 Trigger output 1
Pin18 Trigger output 2
Pin19 Trigger output 3
Pin20 Trigger output 4
Pin21 Trigger output 5
Pin22 Trigger output 6
Pin23 Trigger output 7
Pin24 Trigger output 8
Pin25 Ground
Pin01
Trigger input 1

Trigger inputs 1-8 can also be used to control starting and stopping of saving data to disk. The button "Pause save" is controlled by 2 reserved trigger codes. These (8-bit) codes are defined in the CFG file. Trigger edges unlock or lock the "pause save" button, manual control of the pause button overrides the trigger pulses. Example of .cfg text:
PauseOff="254 //-1 is disabled, 0-255 is enabled"
PauseOn="255 //-1 is disabled, 0-255 is enabled"

Note that when the trigger inputs are not connected, they will be digital "1", so with the above .cfg, toggling trigger 1 and leaving the other pins unconnected, the pause button will switch on/off.
Pin02
Trigger input 2
Pin03
Trigger input 3
Pin04
Trigger input 4
Pin05
Trigger input 5
Pin06
Trigger input 6
Pin07
Trigger input 7
Pin08
Trigger input 8
Pin09
Trigger input 9
  
Pin10 Trigger input 10  
Pin11 Trigger input 11  
Pin12 Trigger input 12  
Pin13 Trigger input 13  
Pin14 Trigger input 14  
Pin15 Trigger input 15  
Pin16 Trigger input 16  
Pin17 Trigger output 1  
Pin18 Trigger output 2  
Pin19 Trigger output 3  
Pin20 Trigger output 4  
Pin21 Trigger output 5  
Pin22 Trigger output 6  
Pin23 Trigger output 7  
Pin24 Trigger output 8  
Pin25 Trigger output 9  
Pin26 Trigger output 10  
Pin27 Trigger output 11  
Pin28 Trigger output 12  
Pin29 Trigger output 13  
Pin30 Trigger output 14  
Pin31 Trigger output 15  
Pin32 Sample-rate clock  
Pin33    
Pin34    
Pin35    
Pin36 5 Volt  
Pin37 Ground  
Bit 00 (LSB)
Trigger Input 1 (High = trigger on)
Bit 01
Trigger Input 2 (High = trigger on)
Bit 02
Trigger Input 3 (High = trigger on)
Bit 03
Trigger Input 4 (High = trigger on)
Bit 04
Trigger Input 5 (High = trigger on)
Bit 05
Trigger Input 6 (High = trigger on)
Bit 06
Trigger Input 7 (High = trigger on)
Bit 07
Trigger Input 8 (High = trigger on)
Bit 08
 Trigger Input 9 (High = trigger on)
Bit 09
 Trigger Input 10 (High = trigger on)
Bit 10
 Trigger Input 11 (High = trigger on)
Bit 11
Trigger Input 12 (High = trigger on)
Bit 12
Trigger Input 13 (High = trigger on)
Bit 13
 Trigger Input 14 (High = trigger on)
Bit 14
Trigger Input 15 (High = trigger on)
Bit 15
 Trigger Input 16 (High = trigger on)
Bit 16
High when new Epoch is started
Bit 17
Speed bit 0
Bit 18
Speed bit 1
Bit 19
Speed bit 2
Bit 20
High when CMS is within range
Bit 21
Speed bit 3
Bit 22
High when battery is low
Bit 23 (MSB)
High if ActiveTwo MK2