| 摘要 |
<p>The invention is characterized by the use of electronic scanners independently controlled by a control unit, said scanners cyclically scanning in an autonomous manner the matrices of the contacts which are assigned to them and the control unit cyclically observing the scanners so that when a scanner detects the change in state of a contact, the control unit collects from said scanner the georgraphical data of this contact and causes, during a determined time the display of the number of said contact and possibly signals the category to which it belongs. This signalling can also, according to its category, be accomplished by an acoustic alarm.</p> |
