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Reference Manual
IP2030/RM, Rev AA
Section 2: Control Unit Overview
June 2014
Section 2: Control Unit Overview4
2.2.2 4–20mA HART transmitter input options
4–20mA HART transmitter input options:
The Mobrey MCU901 Standard control unit and the Mobrey MCU90F Logging control
unit accepts one 4–20mA or HART transmitter input
The Mobrey MCU902 Differential control unit accepts two HART transmitter inputs
Note
The Mobrey MCU900 Series is designed for non-hazardous (safe) area installation, but
can be connected to a transmitter installed in a hazardous area.
See Appendix B: Product Certifications for the control unit certifications.
2.2.3 Control functionality
Control functionality is provided by five SPDT voltage-free contact relays in the control unit
(see Figure 2-2 on page 4). The five relay outputs are fully field adjustable to perform a wide
variety of control, fault indication, or alarm duties.
For applications where the control unit functionality is linked to other external events, there are
two digital input ports for accepting contact closure signals.
The isolated 4–20 mA signal output from the Current Output of the control unit is driven by a
Primary / Process Value (PV) e.g. level.
Figure 2-2. Typical application using a Mobrey MCU900 Series control unit
A. Mobrey MSP Series Level Transmitter E. Pump
B. Mobrey MCU900 Series Control Unit F. Transmitter Bottom Reference
C. 4–20 mA signal output G. 4–20 mA and HART signal input
D. Relay
B
E
E
20mA
4mA
F
D
D
C
A
G