Carrier Air Conditioner Control Module Communication, Carrier Comfort Network CCN Interface

Control Module Communication

RED LED — Proper operation of the control boards can be visually checked by looking at the red status LEDs (light- emitting diodes). When operating correctly, the red status LEDs should be blinking in unison at a rate of once every 2 seconds. If the red LEDs are not blinking in unison, verify that correct power is being supplied to all modules. Be sure that the Main Base Board (MBB) is supplied with the current soft- ware. If necessary, reload current software. If the problem still persists, replace the MBB. A red LED that is lit continuously or blinking at a rate of once per second or faster indicates that the board should be replaced.

GREEN LED — The MBB has one green LED. The Local Equipment Network (LEN) LED should always be blinking whenever power is on. All other boards have a LEN LED which should be blinking whenever power is on. Check LEN connections for potential communication errors at the board J3 and/or J4 connectors. Communication between modules is ac- complished by a 3-wire sensor bus. These 3 wires run in paral- lel from module to module. The J4 connector on the MBB pro- vides both power and communication directly to the marquee display only.

YELLOW LED — The MBB has one yellow LED. The Carrier Comfort Network (CCN) LED will blink during times of network communication.

Carrier Comfort Network (CCN) Interface —

The 30GTN,R chiller units can be connected to the CCN if desired. The communication bus wiring is a shielded, 3-conductor cable with drain wire and is supplied and installed in the field. The system elements are connected to the commu- nication bus in a daisy chain arrangement. The positive pin of each system element communication connector must be wired to the positive pins of the system elements on either side of it. This is also required for the negative and signal ground pins of each system element. Wiring connections for CCN should be made at TB3. Consult the CCN Contractor’s Manual for fur- ther information.

NOTE: Conductors and drain wire must be 20 AWG (Amer- ican Wire Gage) minimum stranded, tinned copper. Individual conductors must be insulated with PVC, PVC/nylon, vinyl, Teflon, or polyethylene. An aluminum/polyester 100% foil shield and an outer jacket of PVC, PVC/nylon, chrome vinyl, or Teflon with a minimum operating temperature range of –20 C to 60 C is required. Wire manufactured by Alpha (2413 or 5463), American (A22503), Belden (8772), or Columbia (02525) meets the above mentioned requirements.

It is important when connecting to a CCN communication bus that a color coding scheme be used for the entire network to simplify the installation. It is recommended that red be used for the signal positive, black for the signal negative, and white for the signal ground. Use a similar scheme for cables contain- ing different colored wires.

At each system element, the shields of its communication bus cables must be tied together. If the communication bus is entirely within one building, the resulting continuous shield must be connected to a ground at one point only. If the commu- nication bus cable exits from one building and enters another, the shields must be connected to grounds at the lightning sup- pressor in each building where the cable enters or exits the building (one point per building only). To connect the unit to the network:

1.Turn off power to the control box.

2.Cut the CCN wire and strip the ends of the red (+), white (ground), and black (–) conductors. (Substitute appropri- ate colors for different colored cables.)

3.Connect the red wire to (+) terminal on TB3 of the plug, the white wire to COM terminal, and the black wire to the

(–) terminal.

4.The RJ14 CCN connector on TB3 can also be used, but is only intended for temporary connection (for example, a laptop computer running Service Tool).

IMPORTANT: A shorted CCN bus cable will prevent some routines from running and may prevent the unit from starting. If abnormal conditions occur, unplug the connector. If conditions return to normal, check the CCN connector and cable. Run new cable if necessary. A short in one section of the bus can cause problems with all system elements on the bus.

Table 2 — Thermistor Designations

THERMISTOR		PIN
		CONNECTION	THERMISTOR INPUT
NO.
		POINT
T1		J8-13,14 (MBB)	Cooler Leaving Fluid
T2		J8-11,12 (MBB)	Cooler Entering Fluid
T3		J8-21,22 (MBB)	Saturated Condensing
			Temperature, Ckt A
T4		J8-15,16 (MBB)	Saturated Condensing
			Temperature, Ckt B
T5		J8-24,25 (MBB)	Cooler Suction Temperature,
			Ckt A (EXV Only)
T6		J8-18,19 (MBB)	Cooler Suction Temperature,
			Ckt B (EXV Only)
T7		J5-11,12 (EXV)	Compressor Suction Gas
			Temperature, Ckt A (EXV Only)
T8		J5-9,10 (EXV)	Compressor Suction Gas
			Temperature, Ckt B (EXV Only)
T9		J8-7,8 (MBB)	Outdoor-Air Temperature
			Sensor or Dual Chiller LWT
			Sensors (Accessory)
T10		J8-5,6 (MBB)	Remote Space Temperature
			Sensor (Accessory)
	LEGEND
EXV — Electronic Expansion Valve
MBB — Main Base Board

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