Rockwell Automation 1734sc-IE4CH E+H Instruments via HART to PlantPAx User Manual - Manual (Page 128)

128 Rockwell Automation Publication PROCES-UM002A-EN-P - July 2014
Appendix I Deltabar S Differential Pressure
This example shows the level measurement with Deltabar S.
Measured Variable
Differential pressure, from which flow (volume or mass current) and level (level,
volume or mass) are derived.
Signals from Instrument to Control System
h = Δ
p
ρ g
+
+
–
–
h
➀
➂
➁
Item Description
1 Level measurement via impulse piping and PMD70
2 Level measurement with FMD76
3 Level measurement with FMD78
h Height (level)
p Differential pressure
Density of the medium
g Gravitation constant
Signal Details
Output signal 4...20 mA with superimposed digital communication protocol HART 5.0, 2-wire
Signal range 4...20 mA HART
3.8 mA to 20.5 mA
Signal on alarm 4...20 mA HART
Options
• Max. alarm*: can be set from 21...23 mA
• Keep measured value: last measured value is kept
• Min. alarm: 3.6 mA
*Factory setting: 22 mA