The wiring recommendations for the communication ports on the automation servers, BACnet/IP devices, RP controller expansion modules, and Operator Display devices apply to wires and cables used for RS-485 communications, LonWorks communications, USB connections, Ethernet connections, sensor bus connections, room bus connections, and RP controller Modbus network connections. Always use the recommended cables and wires.
For AS-P servers, the LonWorks wiring is made to the removable terminal blocks. The connections for RS-485 are made to the removable terminal blocks, and the connections for Ethernet and USB are made to the electronics module.
For AS-B servers, the connections for RS-485 are made to the removable terminal blocks and can be done before the AS-B server is installed on the DIN rail. The connections for Ethernet and USB are made directly to the device.
BACnet/IP Controller – MP controllers have communication ports for Ethernet and USB as well as an RS-485 port dedicated for the sensor bus. All connections are made directly to the device.
BACnet/IP Controller – IP-IO modules have communication ports for Ethernet and USB. All connections are made directly to the device.
BACnet/IP Controller – RP controllers have communication ports for Ethernet and USB, as well as two configurable RS-485 ports, which can be configured for the sensor bus, room bus, or Modbus network. All connections are made directly to the device.
RP controller expansion modules have communication ports for room bus. All connections are made directly to the device.
Operator Display devices have communication ports for Ethernet and USB. All connections are made directly to the device.
The information in this section provides recommendations for the RS-485 interface port configuration between the automation server and RS-485 network devices. This information is intended to supplement existing guides for the automation server and for the various RS-485 network devices.
For more information, see RS-485 Communications .
Twisted pair cables should be used between the FTT-10 interface on the AS-P server terminal base and the TP/FT-10 LonWorks network. The cables should conform to the standard EN 50173-1.
Standard USB cables should be used for connection to the USB host and device ports on the automation server, BACnet/IP device, and Operator Display. The recommended maximum cable length is 3 m (10 ft).
Standard Ethernet cables with RJ45 connectors should be used for connection to the Ethernet 10/100 port(s) on the automation server, BACnet/IP device, and Operator Display.
Standard UTP Ethernet cables are recommended for the network connections.
Shielded network cables can be used on cable sections extending through noisy electrical environments. However, shielded network cables cause ground loops. The grounded RJ45 network connector passes the local ground from a device to the shield of the cable, which in turn passes to the ground of the subsequent device. The devices can be automation servers, BACnet/IP devices, or third-party IP controllers, interface devices, network switches or routers, or telecom switch equipment.
Shield-induced ground loops can cause the following problems:
Degraded performance on communications network
Interruption of communication-dependent process control execution
Unstable operation and/or restart of the two devices
Damage to one or both devices
The objective is to minimize the potential problems created with ground loops in the facility. The effects and risks with ground loops are reduced when the devices are served from the same AC power distribution panel and the devices are in the same general area of the facilities' metal and grounding structure.
Cat 5 (or higher) cables with eight conductors (four twisted pairs) and RJ45 connectors should be used for connection to the BACnet/IP controller's RS-485 port that is used for the sensor bus and the RJ45 port(s) on the SpaceLogic Sensor devices. On an MP controller, the cable is connected to the Sensor Bus port. On an RP-C controller, the cable is connected to the RS-485 port that is configured for the sensor bus. By default, the RP-C controller's Sensor Bus port (RS-485 Com A) is configured for the sensor bus. For more information, see RP-C Communication Ports .
The wire size (cross-sectional area) should be 22 to 26 AWG (0.34 to 0.14 mm²). The sensor bus cables should be rated for the target environment. For example, when the BACnet/IP controller is installed in space handling conditioned air or return air, the cables should be plenum-rated. The cables should be located away from external electrical noise sources such as high voltage cables or signal cables, which can cause data communication problems. The maximum total length of the sensor bus is 61 m (200 ft).
UTP (unshielded twisted pair) cables are recommended for the sensor bus.
Shielded cables are not useful to use for the sensor bus, because the RJ45 receptacles on the BACnet/IP controllers and SpaceLogic Sensor devices do not support grounding of the shield.
The RP-C room bus allows RP controller expansion modules and multi-sensors to be connected to the controller for motion detection, luminosity measurements, communication with remote control (RP-C-RC-BLE), and control of electric lights and window blinds.
Cat 5 (or higher) cables with eight conductors (four twisted pairs) and RJ45 connectors should be used for connection to the RP-C controller's RS-485 port that is configured for the room bus and the RJ45 port(s) on the RP controller expansion modules and multi-sensors. By default, the RP-C controller's Room Bus port (RS-485 Com B) is configured for the room bus. For more information, see RP-C Communication Ports .
The wire size (cross-sectional area) should be 22 to 26 AWG (0.34 to 0.14 mm²). The room bus cables should be rated for the target environment. For example, when the RP-C controller is installed in space handling conditioned air or return air, the cables should be plenum-rated. The cables should be located away from external electrical noise sources such as high voltage cables or signal cables, which can cause data communication problems. The maximum total length of the room bus is 72 m (236 ft).
UTP (unshielded twisted pair) cables are recommended for the room bus.
Shielded cables are not useful to use for the room bus, because the RJ45 receptacles on the RP-C controllers and RP controller expansion modules and multi-sensors do not support grounding of the shield.
The RP-C Modbus RTU (RS-485) subnetwork allows standard Modbus devices and the KNX Modbus gateway (RP-C-EXT-KNX) to be connected to the controller.
You need to configure which RS-485 port on the RP-C controller to use for the Modbus network. You can configure to use either the Sensor Bus port (RS-485 Com A) or Room Bus port (RS-485 Com B). For more information, see RP-C Communication Ports .
Cat 5 (or higher) cables with eight conductors (four twisted pairs) and RJ45 connectors should be used for connection to the RP-C controller's RS-485 (RJ45) port. For more information, see RJ45 Pinout for the RS-485 Ports of the RP-C Controller .
The wire size (cross-sectional area) should be 22 to 26 AWG (0.34 to 0.14 mm²). The Modbus cables should be rated for the target environment. For example, when the RP-C controller is installed in space handling conditioned air or return air, the cables should be plenum-rated. The cables should be located away from external electrical noise sources such as high voltage cables or signal cables, which can cause data communication problems. The maximum total length of the Modbus (RS-485) network is 72 m (236 ft).
UTP (unshielded twisted pair) cables are recommended for the RP-C Modbus network.
Shielded cables are not useful to use for the RP-C Modbus network, because the RJ45 receptacles on the RP-C controllers do not support grounding of the shield.