Model 2002 Vacuum Gauge Page 28 of 37
8. 4-20 mA Interface Option Board
The Relay option board in the Model 2002 operates off of the set points defined by the user and
programmed into the Model 2002 microprocessor. For more information about configuring these set points
refer to Section 3 of this manual.
The 4-20 mA interface board is available as an option for the Model 2002. This board provides dual current
channels linearly proportional to the HPM 2002’s pressure reading. Please note that use of the Model 2002
with this option requires a CPU with firmware for version 1.6 or later.
8.1. 4-20 mA Interference
Connector Pin Assignments
Pin Connection
1.............................................................................................................Internal loop power out (+) channel 1.
3...................................................................................................................................... Loop in (-) channel 1.
8.............................................................................................................Internal loop power out (+) channel 2.
7...................................................................................................................................... Loop in (-) channel 2.
The 4-20 mA board can only be operated with internal loop power.
A schematic (Figure 8.2) is attached to show the proper method to wire into a loop.
Symptom: Fixed display, regardless of pressure
Action: 1. Check sensor for contamination.
Model 2002
Rear Panel Detail
Fig 8.1