| 摘要 |
An interface unit (30) responds to a signal (Vt dependent on a measured parameter, such as torque, and provides an output to an auxiliary unit (40) under the control of a microprocessor (35). The auxiliary unit (40) is connected to the interface unit (30) by a three-line connection (80) two of which wires (81, 82) enable power transfer and the third (83) of which provides bi-directional data transfer. Associated with microprocessor (35) is ADC (36) responsive to the signal (Vt) and to an input of which the date line (83) is connected, a DAC (37) and an analog network (38) connecting the output of the DAC (36) to the data line (83).an initialisation routine (fig.2) established on power-up over a set period tau determines the status of a plurality of bit levels supplied from auxiliary unit(40) to interface unit (30). The interface unit (30) enters a mode of operation dependent in the bits received. One mode is a calibration mode for signal Vt on the data line (83). The ADC (36) controls the DAC (37) to provide an analog output or as a switch to provide a digital output, the output being manipulated according to the calibration established by the microprocessor (35). |
