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BHGE
Analog with Discrete Safety Demand (A/DSD)
The Analog with Discrete Demand configuration is: 4 - 20 mA power input with superimposed
HART
®
communications for control system and 24 VDC 2 wire for Safety System (Figure 14).
Figure 14 Analog with Discrete Safety Demand (A/DSD) Configuration
HART
®
Wiring Guidelines
In order for the SVI II ESD to communicate, the SVI II ESD must be physically connected to a
HART
®
compliant network. “Connecting to the Control Loop” outlines wiring the SVI II ESD.
Connecting to the Control Loop
The SVI II ESD positioner
MUST BE
grounded according to local regulations. It is important to
maintain correct polarity at all times, otherwise the positioner may not operate properly. Physi-
cally connect the SVI II ESD to the HART
®
loop using a cable specified by Field Comm
®
. A shielded
cable is recommended.
To connect the Control Loop to the SVI II ESD:
1. Connect one end of the cable to the control loop's 4 - 20 mA output.
2. Remove the threaded wiring covers on the positioner.
3. Connect the other end of the cable to the SVI II ESD. There are two threaded
openings on the positioner. Use the opening with the red plastic insert.
4. Maintain po and - respectively.
SVI II ESD
Setpoint 4- 20 mA+ HART
4 Wire Solution -Safety Function Triggered by Discrete 0 - 24 VDC Signal (3 VDC = Safety Trip)
Control System
AO
DO
Safety System
Safety Trip Signal Discrete 3 VDC- 24 VDC
or Safety System
