Carrier 33ZCSECTRM Dokumentacja Pobierz pdf (Strona 10)

NETWORK SYSTEM DESIGN INFORMATION

Design Considerations —

A VAV system consists of

a number of air terminals, an air source, and one or more CCN

bus segments. The CCN bus is used by the terminals and air

sources to exchange information. The information shared be-

tween the air source and the air terminals is called linkage in-

formation. The CCN bus segments should follow all specifica-

tions for a CCN bus, except as noted within this application

document.

Air terminals that make up a VAV system must be connect-

ed to the same CCN bus. If the entire CCN system consists

only of these terminals and their air sources, then this bus may

be the primary bus.

Typically there will be other devices on the CCN system. In

this case, the terminals will be placed on a secondary bus. This

secondary bus will be isolated from the primary bus by a CCN

bridge device. Isolation of the secondary bus allows the VAV

system to have complete access to the CCN bus without regard

to bus traffic caused by other CCN devices that are outside of

the VAV system. This is important since proper operation of the

VAV system requires timely communications between the link-

age master and its linked terminals and the air source. Air

sources (when Linkage compatible) may be connected to either

the primary or secondary bus. Multiple VAV systems may oc-

cupy the same bus. The bus will operate at 9600, 19200, or

38400 baud.

Network Design

COMMUNICATION LIMITATIONS

At 9600 Baud

— The number of controllers are limited to 128

zones maximum, with a limit of 8 systems (Linkage Masters

configured for at least 2 zones). Bus length is required not to

exceed 4000 feet with any more than 60 devices on any

1000-foot section. Repeaters are required every 1000 feet with

a maximum of 3 repeaters per bus.

At 19,200 and 38,400 Baud

— The number of controllers are

limited to 128 maximum, with no limit on the number of Link-

age Masters. Bus length is required not to exceed 4000 feet

with any more than 60 devices on any 1000-foot section.

Repeaters are required every 1000 feet with a maximum of

3 repeaters per bus.

COMMUNICATION ADDRESSING — The air terminal

that has the linkage master function enabled will be the highest

addressed terminal within its linked group of terminals. All ter-

minals within the linked group will be addressed with consecu-

tive descending addresses starting from the linkage master.

Each linkage master will utilize broadcast to transmit data to all

the zones in its system, therefore a single zone controller per

bus, which is not the linkage or schedule master, must be desig-

nated as the broadcast acknowledger. One broadcast acknowl-

edger is required per bus.

Each controller will default to an address of 0, 140 when its

application software is initially loaded. Since multiple control-

lers will be on the same bus, a unique address must be assigned

to each controller before the system can operate properly. The

assignment of controller addresses will be performed through

Network Service Tool software.

OCCUPANCY SCHEDULING — Each zone controller is

equipped with a software clock and is capable of performing its

own occupancy scheduling once set up properly. If the control

is configured to use a global occupancy schedule, a global

schedule in an air terminal or networked device is used to de-

termine occupancy status.

In order to provide occupancy status, the software clock

needs to be initialized by a CCN device that contains a hard-

ware clock. The software time clock will require periodic

updates from a time broadcaster in a networked device (with

hardware clock). Devices such as Comfort Controllers, PICs,

and 33CS monitor thermostats all have hardware clocks.

A device with a hardware clock must be set up as a time

broadcaster. If the software clock has not been initialized, the

zone controller will default to the occupied mode.

The zone controller supports the broadcast function. The

zone controller will broadcast its schedule occupancy status

upon transition and every 15 minutes when configured with a

global schedule (schedule number 65 or greater) and as a mas-

ter zone controller. Global schedule enables the master zone

controller to provide occupancy scheduling to all the zone con-

trollers within a given system.

The software time clock must be initialized after any power

failure, either by receiving a Time Broadcast (the controller

will request time from the network), or by a manually updating

the time, through the controller time function.

Network Addressing —

Use the following method

when all the zone controllers are installed and powered, and the

SPT sensors are wired and functioning properly. This method

can be used if no addresses have been set previously. The ad-

dress of an individual zone controller may be set by using the

address search function on the Service Tool software when it is

directly connected to the service port of the zone controller and

the CCN bus is disconnected. This is the standard method of

setting the address.

Addresses may also be set using the Service Tool Address

Search Function if the zone controller is isolated from the CCN

bus.

Each zone controller will default to an address of 0, 140

when its application software is initially loaded. Since multiple

controllers will be on the same bus, a unique address must be

assigned to each controller before the system can operate prop-

erly. The assignment of controller addresses will be performed

through software by using the Address Search function of the

Network Service Tool, as follows:

1. The software recognizes that the Zone Controller's ad-

dress, stored in the zone controller memory, has not been

written yet (this will be true when the unit is first powered

up on the job, or after a jumper-initiated reset).

2. Press the override button on the SPT (terminals J4-14 and

J4-12 are shorted) for 1 to 10 seconds.

3. The zone controller address changes from 0, 140 to 239,

239 for a period of 15 minutes.

4. Use Network Service Tool to change the address from

239, 239 to a valid system address within 15 minutes.

NOTE: If the address is not changed from 239, 239 to

a valid system address within 15 minutes, the control-

ler will revert to address 0, 140 and use of the override

button will cause the address function to repeat. The

operator MUST actively set the address even if the

final desired address is 0, 140.

Zone Controller User Interfaces —

The Zone Con-

troller is designed to allow a service person or building owner

to configure and operate the unit through the CCN user inter-

face. A user interface is not required for day-to-day operation.

All maintenance, configuration, set up, and diagnostic informa-

tion is available through the Level II communications port on

the zone controller. The data port allows data access by an

attached Network Service Tool, ComfortVIEW™, or Comfort-

WORKS

software.

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