An infrared transmitter and a receiver (sensors) is to be connected to the amplifier. The light beam passes the supervised medium. This system operates with modulated infrared light. The transmit power is adjusted automatically for a constant input signal at the receiver. Four measurement ranges resp. measurement modes are available:
Mode 1 - 100% of the overall range correspond to 0-10 V at the analog output. With an offset the 0V threshold can be moved.
Mode 2 - 50% of the overall range correspond to 0-10 V. The measurement range is stretched twice. By the offset, the starting point of the measurement range is fixed to e.g. 20% of transmit power, to even out pollution of the sensor heads. Below 20% the voltage level is 0V, between 20% and 70% the voltage is 0-10 V (corresponding to 50% of the overall measurement range). Above 70% the voltage is always 10 V.
Mode 3 - 25% of the overall range correspond to 0-10 V. The measurement range is stretched fourfold.
Mode 4 - 12,5% of the overall range correspond to 0-10 V. The measurement range is stretched eightfold. In this mode a little change of turbidity achieves the highest change of the output voltage.
The offset is setted by pressing the switch at the front of the device. Alternativly, a setting by the test input is possible. The recent value of turbidity is available at the analog output (0-10V). Additionally, the switching output acts if the voltage level exceeds the adjusted level of the potentiometer (0-10). Like this, a simple fan control can be implemented. The switching output is deactivated if the voltage falls below the adjusted threshold with a hysteresis of approx. 0,2 V. |
