YOKOGAWA YewSeries 80 STED Style S, User Manual

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4-1
IM 01B04J01-02E
Principles of Operation
1
2
3
App
1
2
3
5
6
7
8
4
4.1 mV DC Input Type (STED-1 and STED-7 Types)
The mV DC input signals are converted into digital data in A/D conversion circuit. The
digital data has signal processing (range conversion) in micro-processor to be Pulse Width
Modulation (PWM). The Pulse Width Modulation (PWM) is converted into 1 to 5 V DC or 4 to
20 mA DC signals in output circuit after passing through optical insulation circuit.
Handy
Terminal
Output
Circuit
Input
Processing
Circuit
A/D
Conversion
Circuit
Supply
N–
L+
GND
– –
+
+
–
+
–
Output
Circuit
A
B
Power
Supply
Circuit
Micro-
Processor
Insulation Circuit
F
H
C
D
1
2
+
No switch for
STED-7 type
V/I
SPAN
ZERO
mV DC Input
Output 1 (1 to 5 V DC)
Output 2 (1 to 5 V DC)
Output 3 (4 to 20 mA DC)
F0401.ai
Push Switch
for Adjustment
Insulation Circuit
Figure 4-1 Functional Block Diagram for mV Input Type
Chapter 4 Principles of Operation