In reply to __viking:
You are reading your arguments as strings, and assigning them to enumerated values.
You will need to read the arguments, compare them to a string value, and then assign the enumerated data variable appropriately.
function void set_cfg();
string s_;
cfg = new();
$value$plusargs("end_type_handle=%s", s_);
if (s_ == "EOT") cfg.end_type_handle = EOT;
if (s_ == "DELAY") cfg.end_type_handle = DELAY;
...