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How to

How to


Products: Twisted Pair Adapter
Functionalities: Hardware
Product version: 1.8, 1.9, 2.0, 2.1, 3.0, 3.1, 3.2, 3.3, 2022, 2023, 2024, 7.0, 7.1
12/18/2025

Wiring the Screw Terminals on a Twisted Pair Adapter for Connection of an External 24 VAC/VDC Supply

You wire the screw terminals on a Twisted Pair Adapter to connect the adapter to an external 24 VAC or 24 VDC power supply. Always use the recommended wires (or wires with larger cross-sectional area).

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The Twisted Pair Adapter supports power input from either a standard 24 VAC or 24 VDC source.

To supply power to the adapter, you can use either a transformer or a DC power source:

  • Class 2 (EN 60742) transformer delivering a nominal 24 VAC at 50/60 Hz

  • DC power supply providing a nominal 24 to 30 VDC with sufficient output capacity

For more information, see Twisted Pair Adapter .

The power supply can be the same as the one used for the BACnet/IP controller (MP or RP controller) or automation server (AS-P-3, AS-P or AS-B server). See the following figure for example.

 
action_zoom_plus_stroke Example with AS-P-3 server and RP-C 24 V controller model
Figure: Example with AS-P-3 server and RP-C 24 V controller model

For RP-C 230 V controller models, the 24 VAC output can be used to power the adapter. See the following figure for example.

 
action_zoom_plus_stroke Example with AS-P-3 server and RP-C 230 V controller model
Figure: Example with AS-P-3 server and RP-C 230 V controller model

The adapter features an isolated design for error-resistant installation.

The adapter is based on a half-wave rectified, isolated design, which is complemented with electronic protection components for transient protection, overload protection, and EMC compliance. The design provides galvanic isolation. This helps minimize the risk of damage due to earth currents.

The adapter does not supply power to the twisted pair network.

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This section outlines the recommended cables and wires, specifying the appropriate wire sizes and lengths for the Twisted Pair Adapter.

The recommendations are for guidance only. Other wire sizes and lengths may be used, depending on wiring rules and when appropriate.

Table: Wire Sizes and Lengths for the Twisted Pair Adapter

Terminals

Minimum Cross-sectional Area

Maximum Cable Length

Power input terminals (1, 2)

0.2 mm² (24 AWG) a

According to local wiring rules

Functional earth ground terminals (3, 4)

0.2 mm² (24 AWG) a b

According to local wiring rules

Twisted pair cable network (NET) terminals (5, 6)

0.52 mm² (20 AWG)

1200 m (3900 ft)
  1. Use wires rated for at least 90 °C (194 °F).
  2. The functional earth ground conductor must have a cross-sectional area at least equal to that of the power supply conductor.

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The Twisted Pair Adapter is equipped with the following connectors:

  • 4-position removable screw terminal block (Power input)

  • 2-position removable screw terminal block (NET)

  • RJ45 port labelled Ethernet 10/100

 
action_zoom_plus_stroke Screw terminals and port
Figure: Screw terminals and port
Screw terminals

The screw terminal blocks are used as follows:

  • 4-position, rear terminal block: Power input

  • 2-position, front terminal block: Twisted pair cable network (NET) connection

The screw terminal are wired and connected to an external power supply and a twisted pair cable network as described in the following table.

Recommended screw tightening torque: 0.56 Nm (5 lbf.in)

Table: Screw Terminals

Terminal number

Designation

Usage

Power input

1

L / +

Line (L) lead at 24 VAC, 50/60 Hz or positive (+) lead at 24-30 VDC.

2

N / –

Neutral (N) lead at 24 VAC, 50/60 Hz or negative (–) lead at 24-30 VDC.

Terminals 2, 3, and 4 are internally connected.

3

 
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Functional earth ground.

Terminals 2, 3, and 4 are internally connected.

4

 
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Functional earth ground.

Terminals 2, 3, and 4 are internally connected.

Twisted pair cable network (NET)

5

NET

Twisted pair cable network connection.

Polarity insensitive.

6

NET

Twisted pair cable network connection.

Polarity insensitive.

RJ45 port

The RJ45 port is a standard Ethernet 10/100BASE-TX interface that supports data rates of 10 or 100 Mbit/s. It complies with the IEEE 802.3 Ethernet standard and is used to connect the device to a SpaceLogic BACnet/IP controller or automation server. Actual data throughput may vary depending on the type and length of the transmission medium.

Important:

Before use, check the required ratings for the external 24 VAC or 24 VDC power supply. For more information, see Twisted Pair Adapter .

To wire the screw terminals on a Twisted Pair Adapter for connection of an external 24 VAC/VDC supply

  1. Ensure that the Master/Terminal (M/T) switch on the adapter is set to the desired position ( M or T ). For more information, see Changing the Twisted Pair Adapter Operating Mode .

  2. Loosen the screws of the terminals for power input. For more information, see Twisted Pair Adapter Screw Terminals and Port .

  3. Strip approximately 7 mm (0.3 inch) of the insulation from the end of each wire.

  4. Insert the end of the wire fully into its intended terminals. Ensure that no bare wire strands extend from the terminal.

  5. Tighten the screw using a small flat-blade screwdriver. Ensure that the screw is fully tightened. Use the following recommended screw tightening torque: 0.56 (5 lbf.in).

  6. Repeat steps 2 to 5 until all screw terminals for power input on the adapter are correctly wired. For more information, see Twisted Pair Adapter Screw Terminals and Port .

    Note:

    Terminals 2, 3, and 4 are internally connected.

     
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  7. Use appropriate cable strain relief methods, to help prevent any load applied to the cable from being transferred to conductor terminations.

See Also

  • Twisted Pair Adapter
  • Twisted Pair Adapter Power Supply
  • Twisted Pair Adapter Screw Terminals and Port
  • Changing the Twisted Pair Adapter Operating Mode
  • Wiring
  • Wire Sizes and Lengths for the Twisted Pair Adapter