System Options
5-30 Manual # 42-02-7223
Serial Hall Call
Direct serial I/O allows hall call buttons/indicators, to be connected to iControl using a simple,
2-wire bus for both communication and power. This serial bus reduces the amount of wiring
required per riser and makes the wiring job much easier and less expensive.
The serial bus uses a +/- 15-volt square wave, sampled for both amplitude and duty cycle, for
communication between devices. The positive-going signal actually reaches +40-volts and is
regulated to +24-volts to drive hall call lamps or other loads.
A “bus driver” is required to provide the output capability necessary to carry the load of multi-
ple, simultaneously lighted lamps. A single controller can have up to four drivers/serial buses
with each bus addressing as many as 980 devices. The photograph below shows a serial hall call
bus driver installed in an iCentral Controller cabinet.
Figure 5.13 Serial Hall Call Bus Driver
Serial Bus connection
117 VAC power to driver
Serial output
from driver
Serial to TCP/IP
conversion for
connection to
System switch.
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