Configured for field signal termination and segment distribution in process automation networks, the Allen-Bradley 1788-FBJB6 (1788-FBJB6 Fieldbus Junction Box) provides direct physical/electrical execution.
Hardware Specifications
Parameter
Specification
Model
1788-FBJB6
Brand
Allen-Bradley
Origin
USA
Weight
0.75 lbs (0.34 kg)
Dimensions
Standard DIN-rail junction box footprint
Operating Temp
-20 to 70 deg C
Power Consumption
Passive bus distribution load
Operating Voltage Range
24 to 32 VDC
Protocol Compatibility
FOUNDATION Fieldbus (H1) / PROFIBUS PA
Media Connections
H1 Media Trunk In/Out, 6 H1 Media Drops
Enclosure Style
Open Style
Mounting Format
DIN-rail mount
FOUNDATION Fieldbus / PROFIBUS PA Connectivity and Channel Isolation
The 1788-FBJB6 junction box routes continuous process control data via FOUNDATION Fieldbus H1 and PROFIBUS PA network protocols across an operational voltage window of 24 to 32 VDC. Designed to interface a main H1 media trunk line with up to 6 field instrument spur drops, the internal bus bar architecture maintains deterministic packet delivery and signal integrity. Dedicated spur-to-trunk branch isolation circuits mitigate signal reflections and crosstalk, shielding the primary network loop from localized field cable short circuits.
Frequently Asked Questions
Q: Does the 1788-FBJB6 junction box support spur line insertion or removal while the fieldbus segment is active?
A: Yes. Live fieldbus spurs can be connected or disconnected without interrupting continuous communication across the main H1 trunk line or affecting operational field instruments on remaining spurs.
Q: How does the 1788-FBJB6 junction box manage trunk line termination?
A: The module accommodates standard external fieldbus terminators across its trunk output terminals to satisfy segment impedance matching requirements for PROFIBUS PA and FOUNDATION Fieldbus layouts.
Field Installation Guidelines
Snap the 1788-FBJB6 junction box securely onto a standard 35 mm DIN rail inside a protective field enclosure.
Connect the primary fieldbus trunk-in and trunk-out cables to the main H1 terminal blocks, applying proper shielding practices.
Wire field instruments to the 6 dedicated H1 drop spur terminals using twisted-shielded fieldbus cable pairs.
Verify that total spur lengths and segment power consumption conform to standard FOUNDATION Fieldbus or PROFIBUS PA distance and voltage drop limits.
Ground all cable shield drains at a single point according to system engineering specifications to prevent ground loops.
