Installation
EST3 Installation and Service Manual
5.40
3-SAC Security Access Control module
Product description
The 3-SAC is a high-speed RS-485 module used to support Card
Reader Controller modules and Keypad Display modules. Events
are passed to the 3-SAC module, then passed to the CPU for
alarm processing.
The 3-SAC has two sets of circuit terminals, and is capable of
Class A or Class B configuration. Each Class B circuit can
handle 31 devices, for a total of 62 devices per module. Class A
circuits can handle 30 devices total.
SAC bus
The 3-SAC Security Access Control module supports the SAC
bus, an RS-485 communication line. When properly constructed,
the SAC bus runs over longer distances, supports more drops,
and is more immune to noise than an RS-232 line.
The SAC bus consists of two lines:
• SAC bus +
• SAC bus –
Recommended cabling
Since our security and access control devices require 24 Vdc, we
suggest that you always use a four-wire cable for the SAC bus
and a 24 Vdc power supply.
For the data wires we suggest unshielded, twisted pair, with
greater than 6 twists per foot, in 14 to 22 AWG (1.50 to 0.25 sq
mm).
For the power wires, we recommend 14 or 16 AWG.
Additional power supply wiring
When an additional power supply is required, you must connect
a circuit common point for correct operation. To establish a
circuit common, connect the –24 Vdc terminal on the additional
power supply to the –24 Vdc terminal of the last device. This
circuit common must be connected to the panel, to every device,
and to the circuit common point of any additional power
supplies.
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