Communications Wiring
The controller communicates primarily through Modbus protocol. It can also be configured to use DMX512, BACnet, and C-Bus communications protocols. Refer to, Powerlink NF3500G4 Controller User’s Guide 63249–420–409 for more information about using the controller with these protocols.
Modbus
The controller includes Modbus communications as a standard feature. ASCII and RTU secondary modes are supported as well as TCP/IP. A computer or building automation system (BAS) may be connected to a controller in one of the following ways:
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A temporary local connection using the front panel RJ45 TCP/IP port.
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A permanent connection, either to a local computer or to a remote computer via a modem that is wired into the wiring compartment’s RS232 or RS485 serial port.
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A permanent connection, either to a local computer or to a remote computer via two RJ45 TCP/IP ports.
DMX512
The controllers include DMX512 communication protocol as a standard feature.
BACnet
The Powerlink controller models listed in the table below provide native BACnet communication capability. They can be integrated into a BACnet system in one of two ways:
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Ethernet (BACnet/IP)
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RS485 (MS/TP)
BACnet/IP
Powerlink controllers can be connected directly to an Ethernet backbone so that the BAS front-end software communicates to each controller temporarily. BAS controllers with Ethernet capability can read status and perform control tasks, such as overriding Powerlink zones On/Off, by communicating on the Ethernet network to each controller. Refer to the BACnet IP Screen and Configuring BACnet/IP for more information.
Primary-Secondary/Token Passing (MS/TP)
Powerlink controllers can be connected to a BACnet BAS on an RS485 network. The BACnet BAS front-end software communicates with the BAS controller directly via Ethernet, which in turn, can communicate to a network of Powerlink controllers via serial communications.
Powerlink controllers operate as a primary node on a MS/TP network (device address 0–127).
C-Bus
Serial communications wiring terminals for permanent connections are located in the low-voltage wiring compartment of the controller. Connect a serial communications cable to the three-pin RS232 port which is found in this compartment. Connect the other end of the cable to the C-Bus network interface device. The connector legend is found on the wiring compartment cover.
See Controller Class 2 Communications Terminals Detail.
C-Bus Communications Cable Diagram
C-Bus Cable-RJ45 Pin Reference
| Controller COM1 Connector | RJ45 Pin Number | Designation | Description |
|---|---|---|---|
| 1 | DSR/RI | Data set ready/ring indicator | |
| 2 | DCD | Data carrier detect | |
| 3 | DTR | data terminal ready | |
| 4 | SGND | Signal ground | |
| GRD | 5 | RD | Receive data |
| TX | 6 | SD | Send data |
| RX | 7 | CTS | Clear to send |
| 8 | RTS | Ready to send |
Communications Overview
The Powerlink G4 system contains two levels of communication networks, subnet and automation (see Typical Automation and Subnet Communications Network).
The first level of communications is the device-level network called the subnetwork, or subnet. The subnet connects these Powerlink G4 components.
Up to 16 control buses, which can be located in multiple panelboards, can be controlled from a single controller. The subnet carries command signals from the controller to the appropriate control bus, which in turn, instructs the proper circuit breakers to remotely switch. Through the subnet, the controller also polls the control buses for the status of the remotely operated circuit breakers. In addition to providing the communications path to the control buses, the subnet wiring also provides a 24 Vdc source for powering the control buses and providing power to operate the remotely operated circuit breakers.
The second level of the communication network connects the system (one or more controllers) to devices such as personal computers, modems, or a building management system with the appropriate interface drivers. This communication network is referred to as the automation network.
Typical Automation and Subnet Communications Network
Subnet Communications
A subnet communications network is necessary whenever two or more panels are to be controlled from a single controller.
Subnet Components
In a subnet network, the primary panel contains the controller and power supply. Other panels connected to the controller are referred to as secondary panels.
The components of the subnet communications wiring are the controller, power supply, control buses, secondary address selectors, and secondary bus interconnect cable.
Subnet System Communications Wiring
Subnet Communications Component Wiring
Subnet Wiring
The power supply, located in the primary panel, is connected to each secondary address selector in a daisy chain. See Subnet Wiring Detail. Only one secondary address selector is required for each secondary panel.
Wiring the controller to the subnet is not necessary. The connection between the controller and the power supply provides the subnet communications for the controller.
Subnet Wiring Detail
Secondary Address Selector
The secondary address selector enables the address of the secondary panel to be set. A dial switch on the face of the selector is labeled 0–7, with each number representing a unique address. Address 0 is reserved for the primary panelboard. If the power supply or controller is plugged into any control bus on the subnet, address 0 should not be used as a secondary address.
Secondary Address Selector
Only two control buses may be connected to a secondary address selector. If a second control bus is located in the same secondary panelboard, a secondary bus interconnect cable is required for connecting the secondary address selector to the second bus. For proper operation of the system, always install the secondary address selector on the left control bus. Each secondary address selector must also have its own unique address. If two or more selectors contain the same address, improper operation may result.
Secondary Address Selector Assembly
Subnet Conductors
The National Electrical Code® (NEC™) classifies the Powerlink G4 subnet communications wiring as a Class 1 circuit. Thus, the conductors must be sized and insulated from the line voltage of the panelboard. To meet Class 1 requirements, conductors should be 18 AWG and installed in conduit or an appropriate raceway.
Four conductors are required for the subnet. Two conductors carry 24 Vdc power to the control buses, while the other two are used for the data path. Approved cables are four–wire 18 AWG Class 1 subnet cables such as General Cable 236100, Belden 27326, or equivalent.
The total distance of the conductor length from the power supply to the farthest control bus depends on the power supply voltage. Maximum Wiring Distances in the following are based on nominal voltages.
Maximum Wiring Distances
| Nominal Voltage* | Power Supply Part Number | Maximum Cable Length |
|---|---|---|
| 120 | 400 ft. (122 m) | |
| 220 | 100 ft. (30 m) | |
| 240 | 400 ft. (122 m) | |
| 277 | 400 ft. (122 m) |
With the exception of setting the secondary address selectors, no additional setup is required for commissioning the subnet communications network.
Automation Network Communications
The Powerlink G4 controllers feature an automation network for communicating with other controllers. Three communication ports are available on the controller: RS232, RS485, and Ethernet.
There are three RJ485 ports on the controller. One RJ45 port is located externally on the front of the controller. This port is used to temporarily connect multiple NF3500 controllers to a PC for configuration with LCS software. Two RJ485 ports are located inside the Class 2 wiring compartment and are used for permanent Ethernet communications wiring connection.
Controller Wiring Compartment Components
Controller Class 2 Communications Terminals Detail
RS485
Multiple controllers can be networked together by wiring the system using the RS485 port on the controllers. RS485 Automation Communications Wiring shows a typical configuration where three primary panels are shown (each controlling its own independent subnet.)
A maximum of 247 controllers can be connected together. Use a line repeater for each group of 32 controllers. The maximum cable distances at various baud rates are listed in Maximum Communication Cable Distances.
RS485 Automation Communications Wiring
Maximum Communication Cable Distances
| Baud Rate | Maximum Distances | ||
|---|---|---|---|
| 1–8 Controllers | 9–16 Controllers | 17–32 Controllers | |
| 115,200 | 3000 ft. (914 m) | 3000 ft. (914 m) | 2000 ft. (609 m) |
| 76,800 | 4000 ft. (1219 m) | 4000 ft. (1219 m) | 3000 ft. (914 m) |
| 38,400 | 4000 ft. (1219 m) | 4000 ft. (1219 m) | 3000 ft. (914 m) |
| 19,200 | 5000 ft. (1524 m) | 4000 ft.(1219 m) | 4000 ft. (1219 m) |
| 9600 | 5000 ft. (1524 m) | 5000 ft. (1524 m) | 4000 ft. (1219 m) |
| 4800 | 5000 ft. (1524 m) | 5000 ft. (1524 m) | 4000 ft. (1219 m) |
| 2400 | 5000 ft. (1524 m) | 5000 ft. (1524 m) | 4000 ft. (1219 m) |
| 1200 | 5000 ft. (1524 m) | 5000 ft. (1524 m) | 4000 ft. (1219 m) |
RS485 Controller Connections Using DMX512
A DMX512 primary may be connected to the controller via the internal RS485 port. Refer to DMX512 Communications Wiring Setup. See the instruction bulletin, Powerlink NF3500G4 Controller User’s Guide 63249–420–409 for more information on using the controller with DMX512 systems.
DMX512 Communications Wiring Setup
| Use | FIve-Pin XLR PIN # | DMX512 Function | Controller |
|---|---|---|---|
| Cross reference | 1 | Data Link Common | COM 1: shield |
| Primary Data Link | 2 | Data 1 - | COM 1: NEG (–) |
| 3 | Data 1 + | COM 1: POS (+) | |
| Secondary Data Link (Optional) | 4 | Data 2- | Not used |
| 5 | Data 2 + | Not used |
Automation Communications Wiring Specifications
The National Electric Code (NEC) classifies automation communications wiring as a Class 2 circuit. Conductors may range in size from 24 to 18 AWG and consist of a single set of twisted pair conductors with a shield (Belden 9841 or equivalent). Maximum wiring distance should not exceed 5000 ft (1524 m) at 19,200 baud for eight controllers. See Maximum Communication Cable Distances for more information about maximum communication cable distances at various baud rates.
Shielding and Grounding
The automation network shield should be grounded in one place only, typically at the RS232/485 converter as shown in Alternate RS485 Wiring.
The controller circuitry and associated Class 2 wiring is electrically isolated from all system voltages and earth ground. Maintaining the integrity of this isolation is important for proper operation and performance.
The controller’s input terminals and auxiliary power source are part of the Class 2 circuitry. External devices connected to the controller must meet the isolation requirements and other Class 2 wiring standards. Do not connect the controller to external voltage sources or earth ground.
The RS485 network communications circuit is also part of the Class 2 circuitry. In most applications, the shield of each communications cable will be interconnected at the center terminal of the communications connector. This connection ensures networked controllers are tied together to a common reference potential. The shield must be grounded at only one point in the system. Grounding the shield at multiple points will create a “ground loop” that may disrupt communications or cause damage to the controller circuitry.
Alternate RS485 Wiring
An alternate RS485 wiring scheme that uses a third reference wire is preferred in certain applications:
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When connecting the Class 2 input circuitry to earth/ground cannot be avoided.
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When an external device’s isolation from ground is minimal.
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When the controller is installed on a network with non-isolated devices.
This three-wire method uses a separate reference wire, or pair of wires, to interconnect the center terminal of all communications connectors See Alternate RS485 Wiring.
The shield should remain isolated from the controller and should not be connected to this point. Instead, interconnect the shields using a wire nut.
Connect the shield to ground at only one point.
RS232 Serial Communications
In addition to the RS485 communications port, the controller has an RS232 port for direct connection to personal computers, modems, or other devices that support Modbus ASCII or RTU communications as shown in RS232 Controller Serial Connections.
Because it is a direct RS232 connection, no converter is required. However, the total length of the RS232 wiring should not exceed 50 feet (15 m).
RS232 Controller Serial Connections
RS232 Connection to a Personal Computer
To make the serial communications connection using the RS232 port of the controller, use a standard RS232 nine-pin DB-9 connector and serial cable. Refer to Serial Communication Connections Using the RS232 COMMS Port of the Controller for wiring connection information.
Serial Communication Connections Using the RS232 COMMS Port of the Controller
Installing the Class 2 Barrier
All connections to the wiring compartment of the controller are classified as Class 2 circuits. As such, these circuits must be separated from Class 1, electric light, and power circuits. There are two ways to separate the wiring. The first is to maintain a minimum amount of spacing between the circuits. The second is to install a Class 2 barrier.
A flexible barrier is provided with the controller. The barrier provides circuit separation in situations where maintaining minimum spacing is not practical.
No fittings are required to attach the Class 2 barrier to the controller.
Follow the safety precautions and instructions below to install the Class 2 barrier.
 DANGER |
|---|
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hazard of electric shock, explosion, or arc flash
Failure to follow these instructions will result in death or serious injury.
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Turn off all power supplying this device and the equipment it is installed. Verify that the power is off using a properly rated voltage sensing device.
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Remove the wiring compartment cover by pressing on the retaining tab (or use a small screwdriver), then slide the cover up and away from the controller (See Installing the Class 2 Barrier).
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Remove the conduit plug by pulling down and out on the conduit plug.
Installing the Class 2 Barrier
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Thread the optional tie wrap (supplied) through the holes on the controller as shown in Securing the Class 2 Barrier.
Securing the Class 2 Barrier
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Locate and remove a knockout on the top of the panelboard near the controller. If not using a conduit, apply a fitting where the knockout was removed. This will protect the wires coming into the panelboard.
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Pull the Class 2 wires into the panelboard through the hole in the panelboard.
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Determine the length of the barrier by measuring the distance from where the wires enter the panelboard to the controller wiring compartment.
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Cut the barrier slightly longer than the measured length to allow enough of the barrier to enter the wiring compartment.
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Thread the wires into the barrier and slide the barrier up to the hole in the panelboard.
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Cut the wires to length and terminate them according to the input wiring and communication wiring requirements described in the Input Wiring and Subnet Wiring sections.
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Optional: Close the tie wrap around the barrier to secure the wires and barrier to the controller.
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Position the cover over the wiring compartment and snap it into place.