Siemens SITRANS P DS III - Principle of Operation of the Measuring Cell

Description
3.6 Principle of operation
SITRANS P DS III with PROFIBUS PA
28 Operating Instructions, 06/2013, A5E00053276-07
● The data specific to the measuring cell, the electronics data, and the parameterization
data are stored in two EEPROMs
⑥. The first memory is linked with the measuring cell,
the second with the electronics.
● The results with the status values and diagnostics data are transmitted cyclically over the
PROFIBUS PA. Parameterization data and error messages are transmitted acyclically by
SIMATIC PDM.
Operation
● The buttons
⑧ can be used to call up individual functions, so-called modes.
● If you have a display
⑨, you can track the mode settings and other messages on it.
3.6.3
Principle of operation of the measuring cell
WARNING
Destruction of the seal diaphragm
Danger of injury or damage to device
If the seal membrane is destroyed, the sensor may also be destroyed. If the seal
membrane is destroyed, no reliable measured values can be output.
Hot, toxic and corrosive process media can be released.
• Ensure that the material of the device parts wetted by the process medium is suitable for
the medium. Refer to the information in Technical data (Page 191).
• Make sure that the device is suitable for the maximum operating pressure of your
system. Refer to the information on the nameplate and/or in Technical data (Page 191).
• Define maintenance intervals for regular inspections in line with device use and
empirical values. The maintenance intervals will vary from site to site depending on
corrosion resistance.
In the following sections, the process variable to be measured is called general inlet
pressure.
Overview
The following modes of operation are described:
● Gauge pressure
● Absolute pressure
● Differential pressure and flow rate
● Level
The following process connections are available, for example:
● G1/2 B, 1/2-14 NPT
● Male thread: M20