Introduction—ASC and N2 Bus Networking and Troubleshooting Guide 43
Zone Bus Communications
The Zone Bus is a 2-wire communications bus that allows a computer to
communicate with the ASC to download the ASC’s data base and to
communicate with Zone Terminals and M100s. A third wire is used for
24 VAC power to the Cable Pro, Zone Terminal, and CBLCON. The
Zone Bus has the following specifications:
Table 8: Zone Bus Specifications
Type
Multidrop serial communications bus
Speed
1200 baud (bits per second)
Recommended Cable Type
18 AWG with shield (Belden 8760) or
24 AWG with no shield (unshielded telephone cable)
Maximum Bus Length
500 feet (150 meters) with 18 AWG cable or
50 feet (15 meters) with 24 AWG cable
Maximum Number of Devices
24
Range of Addresses
0 to 63
Voltages
Logic High-Voltage
Logic Low-Voltage
4 VDC minimum (approx.)
1 VDC maximum (approx.)
Data Transmission
1 Start Bit (low level)
8 Data Bits (least significant bit first)
1 Stop Bit (high level)
Each s
ubordinat
e device (e.g., M100C) monitors the bus and responds only
to
messages to its address. The bus data maintains integrity in the presence
of transient pulses up to 40 volts peak positive or negative having a
duration of up to 10 microseconds and repetition rates up to 100 per
second. 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.
Zone Bus
Description
Summary of Contents for METASYS ASC
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