App-34
IM WT310E-01EN
Appendix 7 Block Diagram
Block Diagram
VOLTAGE
±
LPF
500 Hz
LPF
500Hz
A/D
Isolator
Isolator
Zero
crossing
Detector
Peak
Detector
CURRENT
±
External current
sensor input
(EXT, option)
Voltage input circuit
Current input circuit
Input element 1
Input elements 2 and 3
FPGA
CPU
7 segment
LED
USB port
(PC)
GP-IB
or
RS-232
Ethernet
(option)
D/A output
(option)
KEY
Voltage input
Current input
A/D
Zero
crossing
Detector
Peak
Detector
LPF
500 Hz
Isolator
CURRENT
Current input circuit
Current input
A/D
Zero
crossing
Detector
Peak
Detector
WT310E current input (CURRENT INPUT)
±
External current
sensor input
(EXT, option)
Input Signal Flow and Process
Input elements 1 through 3 consist of a voltage input circuit and a current input circuit. The input
circuits are mutually isolated. They are also isolated from the case.
The voltage signal that is applied to the voltage input terminal (VOLTAGE, ±) is normalized using the
voltage divider and the operational amplifier (op-amp) of the voltage input circuit. It is then sent to a
voltage A/D converter.
The current input circuit is equipped with two types of input terminals, a current input terminal
(CURRENT, ±) and an external current sensor input terminal (EXT). Only one can be used at any
given time. The voltage signal from the current sensor that is received at the external current sensor
input terminal is normalized using the voltage divider and the operational amplifier (op-amp). It is then
sent to a current A/D converter.
The current signal that is applied to the current input terminal is converted to a voltage signal by a
shunt. Then, it is sent to the current A/D converter in the same fashion as the voltage signal from the
current sensor.