code: def get_current(self, channel):
          
          ret = self.ask("I%dO?" % channel)
          if ret[-1] != "A":
              print("ttiQl355tp.get_current() format error", ret)
              return None
          return float(ret[:-1])
docs: channel: 1=OP1, 2=OP2, AUX is not supported