The BRX Do-More series of programmable logic controllers have built-in high-speed inputs. These inputs can function in Counter, Timer, or Pulse Catch modes. Every CPU will have either 6 or 10 high-speed inputs (HSI) available depending on the model. These inputs can be used for input frequencies from 0 to 250Khz. 250Khz represents 250000 input counts per second that can be coming from devices connected to your PLC like an encoder. Due to the speed of the inputs, they function on the BRX Do-More PLC asynchronous with the PLC scan time.
We will be looking at the wiring of an incremental encoder to our BRX Do-More PLC. The A, B, and Z phases will be connected. Using the high-speed input menus in the Do-More Designer programming software we will specify the counter mode of operation. We will also scale the input so we can determine the revolutions per minute (RPM) rate. This will be monitored on our data view window. Let’s get started with the BRX Do-More PLC High-Speed Input Counter.