| 摘要 |
<p>An interface circuit (70) for use with process controllers permits analog signals (84) to be input to a process controller through a binary interface of the process controller and permits analog signals (94) to be output from the process controller through the binary interface. The input analog signal is converted to a digital word of N bits. An identification or end indication and the N bits of the digital word are transmitted to the process controller at a rate selected for compatibility with the scan time of the process controller. The process controller includes a software routine for recognizing the N bits of the digital word. An equivalent approach is used for outputting analog signals through a binary interface of a process controller. The interface circuit can include multiple channels for inputting or outputting multiple analog signals.</p> |
