Transfer pressure values with units of inches of water between I/NET and LON with a 913/527/731.

[Product_Support]

Issue

Transfer pressure values with units of inches of water between I/NET and LON with a 913/527/731.

Environment

I/NET

Xenta 913/527/731

XBuilder

Cause

When reading pressure from LON, the value is always in metric units, Pascals, on the LON wire. When the value comes into I/NET, it will be a large, unexpected number.

Resolution

To read in a LON pressure value into I/NET:

1. Create two internal points in I/NET.
   1. AO to receive the raw pressure value in Pascals
   2. AI to perform the conversion to inches of water
2. Add a calculation to the AI to perform the conversion: P0*C0
   • P0 = AO created to receive the raw pressure value in Pascals
   • C0 = 0.004 to convert value from Pascals to inches of water
3. Set the connection object in XBuilder:
   • From = LON SNVT_press
   • To = AO to receive the raw pressure value
   The AI should be reading the correct value in units inches of water.

To write a setpoint value out of I/NET to LON:

1. Create two internal points in I/NET:
   1. AO where the user enters desired static setpoint in inches of water
   2. AO to perform the conversion to Pascals
2. Add a calculation to the AO to perform the conversion: P0*C0
   • P0 = AO created to enter desired static setpoint in inches of water
   • C0 = 249 to convert value from inches of water to Pascals
3. Set the connection object in XBuilder:
   • From = AO to perform the conversion
   • To = LON SNVT_press
   The SNVT should be reading the correct value in desired units.