Analog I/O - Siemens CPU 31 Series Technical Data Manual

Technical data of CPU 31xC
6.6 Technical data of the integrated I/O
6.6.2

Analog I/O

Wiring of the current/voltage inputs
The figure below shows the wiring diagram of the current/voltage inputs operated with 2-/4-
wire measuring transducers.
Figure 6-1
Figure 6-2
Measurement principle
31xC CPUs use the measurement principle of actual value encoding. Here, they operate
with a sampling rate of 1 kHz. That is, a new value is available at the peripheral input word
register once every millisecond. This value can then be read via user program (e.g. L PEW).
The "previous" value is read again if access times are shorter than 1 ms.
6-34
Connection of a 2-wire measuring transducer to an analog current/voltage input of
CPU 313C/314C-2
Connection of a 4-wire measuring transducer to an analog current/voltage input of
CPU 313C/314C-2
CPU 31xC and CPU 31x, Technical Data
Manual, 01/2006 Edition, A5E00105475-06