Magnitude Chiller Unit Controller BACnet Communication Module (MS/TP, IP, Ethernet) | General Information
This manual contains the information you need to install the BACnet
Communication Module on a
Magnitude™ Frictionless Centrifugal Chiller Unit Controller, incorporate it into the BACnet network, and maintain it.
Hazard Identification Messages
Dangers indicate a hazardous situation which will result in death or serious injury if not avoided.
Warnings indicate potentially hazardous situations, which can result in property damage, severe personal injury, or death if not avoided.
Cautions indicate potentially hazardous situations, which can result in personal injury or equipment damage if not avoided.
Electric shock hazard. Can cause personal injury or equipment damage.
This equipment must be properly grounded. Connections and service to the Magnitude
Chiller Unit Controller must be performed only by personnel knowledgeable in the operation of the equipment being controlled.
Static sensitive components. Can cause equipment damage.
Discharge any static electrical charge by touching the bare metal inside the control panel before performing any service work. Never unplug cables, circuit board terminal blocks, or power plugs while power is applied to the panel.
This equipment generates, uses and can radiate radio frequency energy and, if not installed and used in accordance with this instruction manual, may cause interference to radio communications. It has been tested and found to comply with the limits for a Class A digital device, pursuant to part 15 of the FCC rules. These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment. Operation of this equipment in a residential area is likely to cause harmful interference in which case the user will be required to correct the interference at his or her own expense. McQuay International disclaims any liability resulting from any
interference or for the correction thereof.
The BACnet Communication Module incorporates a Magnitude Chiller Unit Controller into a
BACnet local area network (LAN) and provides access to the unit controller parameters via BACnet
MS/TP, BACnet IP, or BACnet Ethernet. See Table 2 for a detailed description of each network connection.
The BACnet Communication Module attaches to the upper left section of the Magnitude Chiller’s main unit controller circuit board. This area is labeled “BAS Interface Board” (see Figure 1.) The main unit controller circuit board itself is labeled “Chiller I/O Backplane” and will be referred to as such for the remainder of this document.
Figure 1. BACnet Communication Module Attached to Chiller Unit Controller
BACnet communication module (attached)
The BACnet Communication Module connects the Magnitude Chiller Unit Controller to a building automation system (BAS) on a BACnet local area network. It is the interface for the exchange of
BACnet objects between the network and the unit controller. Refer to the Magnitude Frictionless
Centrifugal Chiller Operation & Maintenance Manual (OM 1034) for unit controller details. For a complete list of available BACnet points, refer to the Magnitude Chiller Unit Controller - Protocol
Document, ED 15117 (all literature available on www.mcquay.com).
IM 963-1 5
Figure 2 shows the important features of the BACnet Communication Module, which include the
LED locations, network connections, and J8 jumper.
Figure 2. BACnet Communication Module Components
Light Emitting Diodes (LEDs)
The BACnet Communication Module has six LEDs to indicate communication activity and data transmission status. These indicators are visible when the communication module is connected to the
Magnitude Chiller I/O Backplane and the unit is powered on. See Figure 2 for LED locations and
Table 1 for descriptions of LED activity.
Table 1. Description of LED Activity
Green Communication module supports a BACnet network. If present, this LED will always be lit when 5VDC power (supplied from the chiller unit controller) is present.
Yellow Indicates local 3.3 VDC power is present.
Yellow Flashes when the communication module transmits data to the chiller unit controller.
Flashes when the communication module receives data from the chiller unit controller.
Flashes when the communication module receives data from the BACnet network.
Yellow Flashes when the communication module transmits data to the BACnet network.
BACnet Network Connector
The BACnet communication module can be used to connect to a BACnet MS/TP, BACnet IP, or
BACnet Ethernet network. There are two separate network connectors available, depending on the type of network that is connected. See Table 2 below.
Table 2. BACnet Network Connection Details
BACnet IP or
An RS485 connector links the BACnet Communication Module to the MS/TP network. The connector port has three pins: + ,
, and Common.
Pin 1 → COM → Common (isolated from host controller)
Pin 2 → Tx/Rc + → EIA485 Transmit/Receive Positive
Pin 3 → Tx/Rc - → EIA485 Transmit/Receive Negative
An RJ45 connector links the BACnet Communication Module to the BACnet IP or BACnet Ethernet network. The LEDs for this connector function as follows:
Green – This LED flashes to indicate Ethernet activity
If configured for
MS/TP, this LED does not flash green, even if it is connected to an active
Yellow –This LED indicates the port speed. The communication module always operates in full-duplex mode. If the output is Off, the speed is 10 mbps. If the output is On, the speed is 100 mbps.
The 16-pin header connects the Chiller I/O Backplane to the BACnet communication module through the bottom of the communication module. The pins are on located on the back side of the of the communication module.
The BACnet Communication Module has a built-in terminating resistor labeled “J8” on the circuit board. The communication module ships with the jumper installed, providing 120 Ohms of end-ofline resistance to the network. Typically, a network is terminated at each end of each segment.
However, it is the responsibility of the system installer/integrator to recommend whether or not to terminate a device within the network. If the device does not require terminating resistance, or if an external terminating resistor is used, the jumper on J8 should be removed. See Figure 2 for location.
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