Johnson Controls METASYS VAV110 Technical Manual page 49

Zone Bus
6 9 F 7 0 F 7 1 F
Communications
Zone Bus
Description
The Zone Bus is a 2-wire communications bus that allows a computer to
communicate with the VAV to download the VAV's data base and to
communicate with Zone Terminals and M100 Actuators. A third wire is
used for 24 VAC power to the CBLPRO, Zone Terminal, and CBLCON.
The bus interface sustains no damage in presence of fault voltages of
24 VAC.
M100C Actuators must be powered with separate transformers; therefore,
only the Zone Bus and Common wires need to be pulled.
The Zone Bus has the following specifications:
Table 15: Zone Bus Specifications
Type
Speed
Recommended Cable Type
Maximum Bus Length
Range of Addresses
Voltages
Logic High-Voltage
Logic Low-Voltage
Data Transmission
The VAV110/111 and VAV140/141 Series Controllers contain an LED
that blinks to indicate Zone Bus activity with or without external
connection. When a PC via CBLPRO communicates with the controller,
the blink rate may appear to be more steady. See Table 37: Zone Bus LED
Indications in the Troubleshooting section of this document for more
information.
Multidrop serial communications bus
1200 baud (bits per second)
2
18 AWG/1.5 mm with shield (Beldon 8760) or
24 AWG/0.6 mm diameter with no shield
(unshielded telephone cable)
500 feet/150 meters with 18 AWG/1.5 mm
50 feet/15 meters with 24 AWG/0.6 mm diameter cable
0 to 63
4 VDC minimum (approximately)
1 VDC maximum (approximately)
1 Start Bit (low level)
8 Data Bits (least significant bit first)
1 Stop Bit (high level)
VAV Controller—Variable Air Volume (VAV) Controller 49
2
cable or