CH1: this trigger counts the number of fired N_trig fired. A trigger is issued when
N_trig > N_th, where N_th can be set just setting a proper VME register.

CH2: this trigger selects the track usefull for the TRD analysis. According to the TRD group
request a trigger is issued if the following condition is satisfied:

(SM0_A && SM10_A) || (SM8_A && SM16_A) || (SM1_A && SM9_A) || (SM7_A && SM17_A) || (SM5_A && SM14_A) ) ||
(SM0_C && SM10_C) || (SM8_C && SM16_C) || (SM1_C && SM9_C) || (SM7_C && SM17_C) || (SM5_C && SM14)_C ) ||

-- EugenioScapparone - 16 Sep 2008