Rockwell Automation 1414-CPZxxxxx_IPZxxxxx Differential Liquid/Gas Pressure Transmitter - Manual (Page 5)

Differential Liquid/Gas Pressure Transmitter 5
Publication 1414-IN014A-EN-P - October 2005
Operation
For normal operation such as 0-100 PSI, the pressure applied to the High port must
be higher than the pressure applied to the Low port. If the pressure connection is
reversed then the transmitter will always output 4 mA or 0 V. If the Low port is left
open to ambient pressure, then the High port is used to measure a positive
pressure and 0 PSI = 4 mA and 100 PSI = 20 mA. For bidirectional operation such as
+/-100 PSI, the pressure applied to the High port should be higher than the
pressure applied to the Low port for a positive output response. Negative pressure
is indicated if the High pressure is less than the Low pressure. In this case –100 PSI
= 4 mA and +100 PSI = 20 mA. Since the transmitter is linear 0 PSI = 12 mA.
Calibration
With both ports open to the ambient pressure (or with both ports equalized at 0
pressure), press and hold the auto-zero button or provide contact closure on the
ZERO terminals for at least 3 seconds. Release the button or terminals and the
device will calculate and store the new zero point. To protect the unit from
accidental zeroing this feature is enabled only when the detected pressure on both
ports is less than 5% of the full range. It is not recommended that the span
calibration be performed in the field unless a high quality calibrator is available.