| 摘要 |
PURPOSE:To discriminate simply whether the abnormality of transmission is caused by an outdoor machine or not, by a method wherein a switching means and a short- circuit member are connected in series between a signal producing means and a signal receiving means while a signal is transmitted under a condition that the switching means is driven under switch-close condition. CONSTITUTION:A switching transistor 4 is put ON and switching elements 51-54 are closed sequentially and selectively. When an indoor machine 2 is connected, the difference of the levels of signals between the collector terminal of the switching element 55 and the collector terminal of the switching transistor 4 becomes large but the difference of the levels of the signals becomes small when the indoor machine 2 is not connected whereby it can be discriminated by a comparing circuit 11 whether the indoor machine 2 is connected. When the abnormality of transmission is generated during controlling respective indoor machines 2, a short-circuit member 12 closes the switching element 55 only which is connected in series while a producing signal in the collector terminal of the switching transistor 4 is received by a photocoupler 6. When there exists no abnormality in an outdoor machine 1, the producing signal becomes the same as the receiving signal, however, it never become the same when there exists abnormality. This may be discriminated by a micro-computer 13 and may be indicated in the indicator of the outdoor machine 1.
|
