Rosemount pressure transmitter
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This post was last edited by sunqiang4444 on 2022-6-15 at 10:09. The older pressure transmitters produced by Rosemount in the early days had pressure units only in kPa, not in MPa, and the handheld device could not convert kPa to MPa. If I install an older-type pressure transducer with a range of 0-32,000 kPa at a certain point on site, and set the DCS to use a range of 0-32 Mpa, then will the DCS be able to display the measured pressure accurately in Mpa units?
As long as the pressure transducer and DCS display accurate calibration, the measured pressure can be shown accurately
The range displayed on the transmitter’s gauge and that set in the DCS actually correspond to the 4-20mA signal transmitted
Thank you! I roughly understand it, but it’s still a bit unclear to me. Because DCS doesn’t know much. What I actually want to say is that the DSC side should set this value to 0-32 MPa; however, the gauge actually installed on site operates in the 0-32000 kPa range. Can the DSC control system display the measured pressure in MPa units?
Sure. The instrument side has already converted the measured values into analog signals, and the function of the DCS analog input module is to convert current/voltage signals into values within the actual range. Therefore, in the DCS section, it is possible to redefine the range unit after the 4-20mA conversion; as long as the corresponding relationship is correct, the values will be displayed accurately.
Sure. The DCS only recognizes the analog signal values from the transmitters; the display and units are handled separately, and are independent of the units and values displayed by the transmitters. The general process by which DCS handles analog signals is as follows: the input card converts 4–20mA signals into values ranging from 0 to 1000 (the default scaling factor, though some cards allow this to be adjusted); this value is then multiplied by a constant to obtain the value that is to be displayed. As for the unit, for DCS it is just a symbol added after the displayed value, and it has nothing to do with the measurement, the value, or the unit. .
It’s completely possible; the DCS signal is in the 4-20mA range, and the unit on the upper-level system can be set arbitrarily as long as the range matches that of the field instrument.
The gauge can be set to MPa