| 摘要 |
PURPOSE:To attain the change in the span in a field under explosive atmosphere by using a 2-wire transmission line so as to send a pulse between a sensor and a receiver side. CONSTITUTION:A hand-held terminal HHT connected to two-wire transmission lines l1, l2 prior to the communication with a sensor, sends a reply request pulse to the sensor and sends a communication pulse in receiving an acknowledge pulse from the sensor. A sensor incorporates a microcomputer MP, stops the transmission of a pulse signal in receiving the reply request pulse from the hand-held terminal HHT to receive the communication pulse, the microcomputer MP decodes the content of the communication pulse to execute the revision corresponding to the content and sends the pulse signal again in receiving the transmission end pulse of the communication pulse in response to the hand- held terminal HHT. Thus, the span or the like of the sensors is changed from a control room when they are installed in explosive atmosphere.
|
