IN19856
- 22 -
Rev 2
A 16-bit value must be sent to the ITV. The lower or least significant 12 bits represent the count
value. Counts sent to the ITV for a desired pressure or vacuum output must be scaled to an integer
value between 0 and 4095.
The “Maximum Pressure Scaling Formula” for converting pressure to counts is:
𝐶𝒐𝒖𝒏𝒕𝒔 = (
𝒅𝒆𝒔𝒊𝒓𝒆𝒅 𝒑𝒓𝒆𝒔𝒔𝒖𝒓𝒆
𝒎𝒂𝒙𝒊𝒎𝒖𝒎 𝒑𝒓𝒆𝒔𝒔𝒖𝒓𝒆
) × 𝟒𝟎𝟗𝟓
Some of the typical pressure unit types are precalculated below in the table. If another type is need
c
ounts can also be determined by using the “Scale Factor Formula”:
𝑪𝒐𝒖𝒏𝒕𝒔 = 𝒅𝒆𝒔𝒊𝒓𝒆𝒅 𝒑𝒓𝒆𝒔𝒔𝒖𝒓𝒆 × 𝒔𝒄𝒂𝒍𝒆 𝒇𝒂𝒄𝒕𝒐𝒓
The following table shows some precalculated the scale factors for the ITV body types and pressure
units
Pressure
Body Type
MPa
kg/cm2
Bar
PSI
KPa
X010
40950.0
4014.70
4095.0
282.33
40.95
X030
8190.0
802.94
819.0
56.46
8.19
X050
4550.0
446.07
455.0
31.37
4.55
2090
(Vacuum)
-51187.5
-4993.90
-5118.75
-352.92
-51.18
Figure 11 - ITV Scale Factors
For example: The desired output pressure is 10 PSI for an X030 ITV. From the table, the scale
factor for this body type is 56.46. Use the
“Scale Factor” formula to obtain the count value.
𝑪𝒐𝒖𝒏𝒕𝒔 = 𝟏𝟎 × 𝟓𝟔. 𝟒𝟔 = 𝟓𝟔𝟒. 𝟔 ≅ 𝟓𝟔𝟓 = 𝟎𝒙𝟎𝟐𝟑𝟓
The calculated count value must be rounded if necessary and converted to hexadecimal.
