function [sDate, sTime, cur_nA, pos] = readPos2(fn, pos_target)
  % line format [sDate, sTime, shPos, Curr, profAvg, profMin, profMax]
  % fn = L:\CPC_Qual_Data\GainCalibrationLog\0710814-000_W000627389_tile2\f_20200518_112402.txt
  % pos_target = 8000;
  sDate = ""; sTime = "";
  cur_nA=0; pos=0;
  iDate = 1; iTime = 2;
  iPos = 3; iCur = 4;
  fid = fopen(fn);
  tline = fgetl(fid);  % skip 1st line
  tline = fgetl(fid); % skip 2nd line
  L1= fgetl(fid);
  while ischar(L1)
    if L1(1:5) == 'Tile_' 
      break; 
    end % if; exit cycle when change direction
    p1 = strsplit(L1);
    pos = str2num(p1{iPos});
    if pos == pos_target
        sDate = p1{iDate}; 
        sTime = p1{iTime};
        cur_nA = str2num(p1{iCur});
        fclose(fid);
        return
    end % if
    L1= fgetl(fid);
  end % while
  fclose(fid);
end  