Analog modules
9.3 SM 336; F-AI 6 x 0/4 ... 20 mA HART
Fail-safe signal modules
Installation and Operating Manual, 01/2010, A5E00085586-10
237
Wiring scheme G: 4-wire transducer, internal sensor supply with module redundancy
Particularity:
●
Short circuit between sensor supply voltage Vsn and Mn+ is handled.
●
It is possible to detect an undervoltage at the transducer by reading back the sensor
supply in the module.
●
It is necessary to incorporate the external elements into the application-specific safety
examination. This means appropriate external elements (e.g., Zener diodes) are needed
to achieve the respective Safety Integrity Level.
Note
1L+ and 2L+ can be fed from one power supply.
/
0
60
$,[P$+$57
60
$,[P$+$57
/
0
9V
0
0
9V
0
0
9V
0
0
9V
0
0
9V
0
0
9V
0
0
/
0
9V
0
0
9V
0
0
9V
0
0
9V
0
0
9V
0
0
9V
0
0
3
/
0
&+
&+
&+
&+
&+
&+
&+
&+
&+
&+
&+
&+
ZLUH
WUDQVGXFHU
Figure 9-28 4-wire transducer, internal sensor supply with module redundancy
For information about the Zener diodes, refer to chapter "Calculation of the residual supply
voltage at the transducer (Page 239)".
