| 摘要 |
<p>A field device for determining or monitoring a process variable in automation technology. The field device meets a safety standard, which is required in a predetermined safety-critical application, comprising: a sensor, which works according to a defined measuring principle; and a control/evaluation unit, which processes and evaluates measurement data delivered by the sensor along at least three redundant and/or diversely designed measurement channels, wherein a redundant analog electrical current interface is provided, via which an electrical current representing the process variable is settable in a two-wire line. The analog electrical current interface is designed triply redundantly wherein the following components are associated with the analog electrical current interface: three electrical current setting channels connected in parallel, a doubly redundant voter, which detects a malfunction in one of the measurement channels and/or the electrical current setting channels a doubly redundant turn off stage, via which a measurement channel, respectively an electrical current setting channel, is turned off, when the voter detects a malfunction in the measurement channel or in the electrical current setting channel.</p> |
