Omega 1002 Manuale Utente

 

There are several trigger methods that can be selected by the user (see 

section 1.4.5): 

 

[Bit1,Bit0 ] 

Descriptions 

[ 0, 0 ] 

 General trigger mode.  
 8254 timer 0 trigger (internal pacer trigger ) or software  
 trigger.  

[ 0, 1 ] 

 External clock trigger mode. 

[ 1, 0 ] 

 Pre-trigger mode. 

[ 1, 1 ] 

 Post-trigger mode. 

 
Note: 

1.   In the general trigger mode, both the 8254 timer 0 and the software 

trigger are used as the A/D trigger signals. The timer 0 and the software 
trigger should not be used at the same time! This means the user 
should not generate a software trigger while the 8254 timer 0 is 
activated! 

2.   In the external clock trigger mode, an external input is taken as the A/D 

trigger signal. A single falling edge of the external trigger will generate 
a single A/D trigger. 

3.   The pre-trigger mode employs the 8254 timer 1. The user should first 

configure timer 1, then set the trigger mode to pre-trigger. Once the 
pre-trigger mode has been activated, it will automatically turn on timer 
1 and start the A/D trigger. This will continue until a falling edge from 
an external trigger signal is received. Any change to the trigger mode 
selection will turn off the pre-trigger mode. 

4.   The post-trigger mode employs the 8254 timer 1. The user should first 

configure timer 1, then set the trigger mode to post-trigger. Once the 
post-trigger mode has been activated, it will automatically turn off the 
timer 1 until it receives a falling edge from an external signal. Any 
change to the trigger mode selection will turn off the post-trigger mode. 

5.   The A/D trigger selection is set to 0 after power-on or hardware reset.