| 摘要 |
A communications apparatus is disclosed which, through a transmitter loop, can conduct two-way communication with a field device. The communications apparatus comprises a branching loop connected in parallel with a load resistor inserted in the transmitter loop, a time constant circuit comprising a capacitor and resistor provided in the branching loop, a switch short-circuiting the resistor in the time constant circuit, and a communication unit receiving, as communication data from the field device, an AC signal component passed through the capacitor and, after an AC signal representative of communication data to allow communications with the field device is applied to the branching loop, superimposing AC signal on an analog signal flowing in the transmitter loop.
|
