UNT Controller—Unitary (UNT) Controller
47
Table 15: Zone Bus Specifications
Specification Description
Type
Multidrop serial communications bus
Speed
1200 baud (bits per second)
Recommended Cable Type
18 AWG with shield (Beldon 8760) or
24 AWG with no shield (unshielded telephone cord)
Maximum Bus Length
150 m (500 ft) with 18 AWG cable or
*30 m (100 ft) with 24 AWG cable
Range of Addresses
0 to 63
Voltages
Logic High-Voltage
Logic Low-Voltage
4 VDC minimum (approximately)
1 VDC maximum (approximately)
Data Transmission
1 Start Bit (low level)
8 Data Bits (least significant bit first)
1 Stop Bit (high level)
*Note: If a CBLPRO-1 and a Zone Terminal are used, the cable length must be limited
to 15 m (50 ft).
The UNT110/111, UNT120/121, and UNT140/141 series controllers
contain an LED that blinks to indicate Zone Bus activity with or without
external connection. During power up, there is a brief delay while the
UNT undergoes a diagnostic reset. The LED will blink once, turn off for
approximately 10 seconds, and turn on again. When a PC communicates
with the UNT via CBLPRO, the blink rate may appear to change; that is, it
may appear to be more steady.
Table 16: Zone Bus LED
Green LED Cause
Off
No power to ASC
On
Zone Bus shorted to common or 24 VAC
Blinking
Normal Communication
The AS-CBLPRO is an interface device used between a computer running
HVAC PRO for Windows and Application Specific Controllers (ASCs).
It is used for database downloading, uploading, or commissioning via the
Zone Bus communication port.
When used with a Zone Bus device, such as the UNT or ZT, the CBLPRO
is strictly an electrical interface between the serial RS-232 port of the
computer and the Zone Bus. CBLPRO operates on 24 VAC drawn from a
UNT over the wire used to make the Zone Bus connections. The data
transfer rate on both the RS-232 and the Zone Bus is 1200 baud.
The connection to the RS-232 COM port of the computer is through a
DB9 or DB25 connector supplied with the CBLPRO. After connecting it,
make sure the CBLPRO is more than 30 cm (1 ft) away from the computer
monitor and system unit.
CBLPRO
Description
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