earth_america
user_standard Log on
action_search_stroke
earth_america
Log on to rate and give feedback 1 2 3 4 5 Log on to rate
0
How to

How to


Products: MP-V, RP-C
Functionalities: Hardware
Product version: 2022
10/25/2022

Connecting a Non-isolated RS-485 Adapter

You connect a Non-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 a Non-isolated RS-485 Adapter (SXWNISORS48510001) when the BACnet MS/TP network includes non-isolated controllers, such as the b3 BACnet family of zone controllers.

Show More
action_close

The Non-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, Non-isolated RS-485 Adapter

RJ45 port and screw terminals, Non-isolated RS-485 Adapter

The following figure shows an example of how a Non-isolated RS-485 Adapter is connected to one of the RS-485 Com ports (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 a Non-isolated RS-485 Adapter used for connection of an RP-C controller to a BACnet MS/TP network and an AS-P server

Example with a Non-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.

Notice

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.

For more information, see Connecting a Non-isolated RS-485 Adapter .

For more information, see RJ45 Pinout for the RS-485 Ports of the RP-C 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)

Table: Screw Terminals, Non-isolated RS-485 Adapter

Terminal

Usage

NOT USED

Not connected.

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

Convenience terminal to interconnect two shield drain wires (incoming and outgoing). There is no electrical connection in the adapter. The shield should be connected to ground at only one location and that is recommended to be at the automation server. The shield should not be connected directly to the RET terminal on the automation server. The transient energy on the drain wire should be conducted to ground and not through the automation server.

For more information, see Wiring the Screw Terminals on a Non-isolated RS-485 Adapter .

For more information, see RS-485 Communications .

Notice

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 a Non-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.

    Note:

    The cable is not included.

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

    Select the RS-485 Com port that is configured for BACnet MS/TP (RS-485) network. For more information, see RP-C BACnet MS/TP Support .For more information, see Allocating Flexible Ports .

     
    action_zoom_plus_stroke

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

See Also

  • Non-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 a Non-isolated RS-485 Adapter