Siemens Metro 21 M216KA Operator's Manual page 283

Block Diagram
SC bus
Figure 12-14 Block Diagram of the 2 AI HS I High-Speed Analog Electronic Module (0/4–20mA, 4-Wire Measuring
Transducer)
ET 200L, ET 200L-SC and ET 200L-SC IM-SC Distributed I/O Device
EWA 4NEB 780 6009-02c
SC Analog Electronic Modules – T echnical Data
Figure 12-14 shows the block diagram of the 2 AI HS I high-speed analog
electronic module (0/4–20mA, 4-wire measuring transducer).
Galvanic
isolation
Logic
and
interface
circuit
Internal
supply
Note
The current limitation applies to both measuring transducers of the 2 AI HS I
analog electronic module.
If a short circuit occurs at one measuring transducer and thus activates cur-
rent limitation, the second measuring transducer does not indicate a valid
value.
ADC
1 M 0 +
A
3 M 0 –
2 M 1 +
A
4 M 1 –
L+
M
12-27