| 摘要 |
<p>PURPOSE:To read measurement signals accurately over a wide range by storing the input and output characteristic data of a photocoupler beforehand automatically in a temporary storage element of a microprocessor at the turning on of an eletric power source or prior to measurement, and calibrating the output of the photocoupler automatically by utilizing these. CONSTITUTION:When the electric power source switch of the measuring device is turned on, a CPU5 drives a relay constituting a signal changing part, thereby changing relay contacts to 11a side. Next, the CPU5 passes the digital quantity stored in a program memory 6 through a D/A converter 8 and a driving circuit 1 and applies analog quantity A1 to a photocoupler 2. At this time, an output B1 is obtained. This value is read via an A/D converter 4 by the CPU5 and is stored in an RAM7. Next, the CPU5 applies another date successively, and stores the same in the RAM7 in the same manner so that the input and output characteristics of the coupler 2 are stored. Next, the contscts of the relay 11 are changed over to the side of the current and voltage to be measured, and thereafter, the CPU knows input voltage from the output voltage of the coupler 2 from the characteristic chart stored in the RAM7 thereby knowing the correct current and voltage to be measured.</p> |
