Current Ratings - Alarm Control Panel And Modules; Combus Operation And Wiring - DSC MAXSYS PC4020 Installation Manual

2.3 Current Ratings – Alarm Control Panel and
Modules
In order for the system to operate properly, the power
output of the alarm control panel and power supply
modules cannot be exceeded. Use the data below to
ensure that the available current is not exceeded.
PC4020 Alarm Control Panel
AUX - 500mA available for devices connected to the
AUX, SAUX+ and PGM terminals and modules con-
nected to Combus terminals. At least 100mA must be
reserved for the Combus. To calculate the amount of cur-
rent required, complete the following chart:
Main Panel Current Calculation
Maximum (Standby or Alarm)
AUX (500mA max.)
SAUX+ (300mA max.)
PGM1 (50/170mA max.*)
PGM2 (50/170mA max.*)
Combus (500mA max.)**
Bell+ (700mA max. continuous)
Total (must not exceed 900mA)
Alarm (for 4 min. maximum)
Bell (2A max.)
* PGM1/PGM2 (Standard Output) = 50mA max.
PGM1/PGM2 (Addressable Loop) = 170mA max.
To calculate Addressable Loop current, see Section
2.8 "AML Device Wiring."
** See "Combus Current Calculation Chart" at right.
NOTE: For UL, ULC and Fire applications, the total
standby AND alarm current cannot exceed 900mA.
PC4020 Module Ratings
The current draw of compatible PC4020 modules is listed
below:
Device .................................................Current Draw (mA)
Keypad (LCD45XX)......................................................... 50
PC4108A Zone Expander ............................................... 30
PC4116 Zone Expander................................................... 30
PC4164-RS Wireless Receiver....................................... 110
PC4701 Fire Module ........................................................ 35
PC4702BP Dual Bell Output Module............................ 75
PC4204 Relay Output Module ....................................... 30
PC4216 Low Current Output Module .......................... 15
ESCORT4580 Audio Assistant ..................................... 150
PC4400 Serial Printer Interface Module ....................... 30
PC4820 Access Control Module .................................... 35
S e c t i o n 2 : I n s t a l l a t i o n
Calculating Total Current Requirement
Once you have determined which modules will draw
power from the main panel, use the following chart to
calculate the Combus current.
Combus Current Selection Chart
Item Current (mA)
Keypad 50
PC4108A* 30
Current required for connected devices =
PC4116* 30
Current required for connected devices =
PC4164-RS 110
PC4701 35
PC4702BP 75
PC4204 30
PC4216* 15
Current required for connected devices =
ESCORT4580 150
PC4400 30
PC4820 35
Total Combus Current =
* These units draw current from the Combus to power
devices external to the module. This current must be added
to the total Combus current. See manufacturer's specifica-
tions for the current draw of each device. Each LED assembly
draws up to 20mA of current.

2.4 Combus Operation and Wiring

The Combus is used by the control panel and the mod-
ules to communicate with each other. The four Combus
terminals of the main panel must be connected to the
four Combus terminals or wires of all modules.
Modules can be home run, connected in a daisy chain or
T-tapped anywhere on the Combus.
The following rules MUST be followed when wiring the
Combus:
1. The Combus must be run in minimum 22-gauge
wire.
2. No module can be more than 1000' (305m) in cable
length from the main control panel.
3. Shielded wire should only be used in areas that
present excessive RF noise or electromagnetic inter-
ference. If shielded wire is used, the maximum dis-
tance a module can be located from the main panel is
significantly reduced. Check the capacitance limit of
a n d W i r i n g
x Quantity Total (mA)
x
x
x
x
x
x
x
x
x
x
x
3