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Explicación de procesos

Explicación de procesos


Productos MP-V, RP-C, RP-V
Funcionalidades: Hardware
Versión del producto: 2022, 2023, 2024
25/10/2022

Connecting an Isolated RS-485 Adapter

You connect an Isolated RS-485 Adapter (via a separate connection cable) to a BACnet/IP controller to convert the controller RS-485 RJ45 interface to screw terminals, which is required to connect the controller to a BACnet MS/TP (RS-485) network. You use an Isolated RS-485 Adapter (SXWISORS48510001) when the BACnet MS/TP network is comprised of isolated controllers, such as MNB BACnet devices (zone controllers) and selected others.

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The Isolated RS-485 Adapter is equipped with an RJ45 port for connection to a BACnet/IP controller RS-485 Com port and a 4-position removable screw terminal block for connection to a BACnet MS/TP (RS-485) network.

 
action_zoom_plus_stroke RJ45 port and screw terminals, Isolated RS-485 Adapter
Figura: RJ45 port and screw terminals, Isolated RS-485 Adapter

The following figure shows an example of how an Isolated RS-485 Adapter is connected to the RS-485 Com B port (RJ45) of an RP-C controller via a Cat 5 (or higher) UTP cable of maximum length 0.3 m (12 in.) and how the BACnet MS/TP network (RS-485) wires from the adapter are connected to the RS-485 Com port screw terminals of an AS-P server.

 
action_zoom_plus_stroke Example with an Isolated RS-485 Adapter used for connection of an RP-C controller to a BACnet MS/TP network and an AS-P server
Figura: Example with an Isolated RS-485 Adapter used for connection of an RP-C controller to a BACnet MS/TP network and an AS-P server
Connection of RJ45 port to BACnet/IP controller RS-485 Com port

A separate connection cable is required to connect the RJ45 port on the RS-485 adapter to the RS-485 Com port (RJ45) on the BACnet/IP controller. The cable is not included and needs to be purchased separately.

Use a Cat 5 (or higher) unshielded, straight-through wired cable with eight conductors (four twisted pairs) and RJ45 connectors. Use a cable with the wire size (cross-sectional area) 22 to 26 AWG (0.34 to 0.14 mm²), a maximum length of 0.3 m (12 inches), and a rating that meets the requirements of the target environment. For example, when devices are installed in a space that handles conditioned air or return air, the cables typically need to be plenum-rated.

Aviso

LOSS OF COMMUNICATION

  • Ensure that the length of the cable for connection of the RS-485 adapter to the controller does not exceed 0.3 m (12 inches).

  • Use a Cat 5 or higher unshielded twisted pair cable with eight conductors (four twisted pairs), a cross-sectional area of 22 to 26 AWG (0.34 to 0.14 mm 2 ), and a rating that meets the requirements of the target environment.

Failure to follow these instructions can result in loss of communication.

Para obtener más información, consulte Connecting an Isolated RS-485 Adapter .

Para obtener más información, consulte RJ45 Pinout for the RS-485 Port(s) of the RP-C Controllers .

Para obtener más información, consulte RJ45 Pinout for the RS-485 Port of the MP-V Controller .

Wiring of screw terminals for connection to BACnet MS/TP network

The four screw terminals are wired and connected to a BACnet MS/TP (RS-485) network as described in the following table.

Recommended screw tightening torque: 0.5 Nm (4.5 lbf.in)

Tabla: Screw Terminals, Isolated RS-485 Adapter

Terminal

Usage

BIAS+

Provides +5 VDC for use to deliver a positive bias to the TX/RX+ data line through an appropriate value resistor. For example, when configuring strong dual end bias such as required by MNB BACnet devices, a 1 kohm resistor would be connected between the BIAS+ and TX/RX+ terminal.

TX/RX+

Data line (+) for connection to the TX/RX+ signal in the BACnet MS/TP twisted pair connecting all devices on the bus.

TX/RX–

Data line (–) for connection to the TX/RX– signal in the BACnet MS/TP twisted pair connecting all devices on the bus.

SHIELD

Provides common (low side) of 5 VDC supply for delivering negative bias to the TX/RX– data signal through an appropriate value resistor. For example, when configuring strong dual end bias such as required by MNB BACnet devices, a 1 kohm resistor would be connected between the SHIELD and TX/RX– terminal. The Isolated RS-485 Adapter removes the need for a separate 5 VDC supply when positioned at the end of the bus.

Para obtener más información, consulte Wiring the Screw Terminals on an Isolated RS-485 Adapter .

Para obtener más información, consulte RS-485 Communications .

Aviso

BACNET MS/TP NETWORK OUTAGE OR PERFORMANCE DEGRADATION

For a BACnet MS/TP network with MNB BACnet devices, ensure you use an isolated RS-485 adapter (SXWISORS48510001) connected to the RP controller Com B port or MP-V controller Com A port.

Failure to follow these instructions can result in BACnet MS/TP network outage or performance degradation.

Aviso

LOSS OF COMMUNICATION

  • Ensure that the length of the cable for connection of the RS-485 adapter to the controller does not exceed 0.3 m (12 inches).

  • Use a Cat 5 or higher unshielded twisted pair cable with eight conductors (four twisted pairs), a cross-sectional area of 22 to 26 AWG (0.34 to 0.14 mm 2 ), and a rating that meets the requirements of the target environment.

Failure to follow these instructions can result in loss of communication.

To connect an Isolated RS-485 Adapter

  1. Connect a Cat 5 (or higher) unshielded, straight-through wired cable with eight conductors (four twisted pairs) with RJ45 connectors to the RJ45 receptacle on the RS-485 adapter.

    Use a cable with the wire size (cross-sectional area) 22 to 26 AWG (0.34 to 0.14 mm²), a maximum length of 0.3 m (12 inches), and a rating that meets the requirements of the target environment, for example, plenum space.

    Aviso

    The cable is not included.

  2. Connect the other end of the cable to the RP controller RS-485 Com B port or MP-V controller RS-485 Com A port.

    The RS-485 Com port needs to be configured for BACnet MS/TP (RS-485) network. Para obtener más información, consulte RP-C BACnet MS/TP Support .Para obtener más información, consulte Allocating Flexible Ports .

     
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You can now install and wire the RS-485 adapter.

Consulte también

  • Isolated RS-485 Adapter Connection and Wiring
  • RP-C BACnet MS/TP Support
  • Allocating Flexible Ports
  • Installing an RS-485 Adapter
  • Wiring the Screw Terminals on an Isolated RS-485 Adapter