Ams trex™ Device Communicator

Figure 5-3: Power and connect to a FOUNDATION fieldbus device
To power a FOUNDATION fieldbus device, the Trex unit needs the FOUNDATION fieldbus
Power Plug. When the Trex unit powers a device, it also provides two terminators and a
power conditioner.
 WARNING
The Trex unit can power only one FOUNDATION fieldbus device in a bench setup.
A. FOUNDATION fieldbus Power Plug
Fieldbus Diagnostics application
User Guide
September 2021
158
User Guide

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Figure 5-4: Connect to an externally-powered fieldbus segment
For small fieldbus segments, the power conditioner and terminators can be contained in a
single wiring block.
Note
You can connect the Trex unit at any convenient place along the fieldbus segment (bus). In
the field, this is typically done at the device or at the fieldbus junction box. The drawing
below is one example.
A. Terminators
B. Power conditioner
C. Fieldbus power supply
D. Host system
5.5
Power a FOUNDATION fieldbus device
The Trex unit can power one FOUNDATION fieldbus device. The Trex unit can provide
approximately 10 volts at 25 mA to power a FOUNDATION fieldbus device. (The Trex unit
will draw approximately 12 mA when it is online)
If you try to apply power from the Trex unit when the device is externally-powered, the
Fieldbus Diagnostics application prevents the Trex unit from supplying power. This
protects the Trex unit from damage.
Note
When the Trex unit powers a FOUNDATION fieldbus device, two internal terminators and a
power conditioner are applied. Ensure the device is not connected to a fieldbus segment,
even if the segment is unpowered.
 CAUTION
Remove the USB cable from the Trex unit before connecting to a device.
User Guide 
Fieldbus Diagnostics application
September 2021
User Guide 
159

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 WARNING
Do not add any external power to the device when the Trex unit is powering the device.
This can blow a fuse inside the Trex unit. The repair/replacement will need to be
completed at an authorized service center. Ensure the device is disconnected from the
loop/segment and no other wires are connected to the device before providing power
from the Trex unit.
Procedure
1. Connect the lead set to the FF terminals on the Trex unit and directly to the
communication terminals on the unpowered device. Ensure no other wires are
connected to the device and there is no power to the device. Do not attach to a
junction box.
2. Connect the FOUNDATION fieldbus Power Plug to the FF pwr terminal and the
positive (red) terminal on the lead set.