new const 
m_flPowerUp = 166,
m_flBeamLength = 173,
m_pBeam = 176,
xtra_ofs_weapon = 4,
xtra_ofs_player = 5

public plugin_init() 
{
   RegisterHam(Ham_Think, "monster_tripmine", "Tripmine_Think_Post", 1);
}

public Tripmine_Think_Post(ent)
{
   if (!pev_valid(ent) || get_pdata_float(ent, m_flPowerUp, xtra_ofs_player) > get_gametime())
      return HAM_IGNORED;
   
   set_pev(ent, pev_nextthink, get_gametime() + 1.0);

   
   static beam; beam = get_pdata_cbase(ent, m_pBeam, xtra_ofs_player);
   static flBeam_Length; get_pdata_float(ent, m_flBeamLength, xtra_ofs_weapon)
   

   if(pev_valid(beam) /*&& flBeam_Length*/)
   {
      client_print(0, print_chat, "* 1) Old BeamLength :[%0.2f]", flBeam_Length)
      
      if( flBeam_Length) {
         
         set_pdata_float(ent, m_flBeamLength, 500.0 ,xtra_ofs_weapon)
         
         client_print(0, print_chat, "* 2) New BeamLength :[%0.2f]", flBeam_Length)
      }
      return HAM_IGNORED;
   }
   return HAM_IGNORED;   
}