Different ranges of SNVT_press, SNVT_press_p, and SNVT_press_f

Issue

  • SNVT_press_p cannot represent a value above 32766 Pa
  • Sending a value of 15psi out of a Menta application using a SNVT_press_p and it is arriving at the receiving controller as 4.75psi.

Product Line

TAC Vista

Environment

  • SNVT_press_p
  • Menta
  • LonMaker/NL220

Cause

All LON communication is transmitted in metric units, so the data sizes are limited by the valid range of Pascals (or kiloPascals for SNVT_press).

Resolution

There are three different SNVT types defined to represent a pressure (gauge) value. SNVT_press, SNVT_press_f, and SNVT_press_p. It is important to recognize the valid ranges of data each one can represent.

Name Units Maximum Minimum
SNVT_press kiloPascals 3,276.70 -3,276.80
psi 475.25 -475.26
inches wc 13,154.74 -13,155.15
SNVT_press_f Pascals 3.40E+38 -3.40E+38
psi 4.94E+34 -4.94E+34
inches wc 1.37E+36 -1.37E+36
SNVT_press_p Pascals 32,766.00 -32,768.00
psi 4.75 -4.75
inches wc 131.48 -131.48