Access control applications 
EST3 Installation and Service Manual  3.23 
Power supply 
The figure shows an independent power source for the CRC. 
This is suggested due to the length of cable from the cab to the 
electrical room. 
Two pairs of wires are used to connect the CRC to the control 
panel. The SAC bus requires one pair for data communication. 
One wire of the second pair is required to maintain a common 
ground between the control panel and the CRC. For details, refer 
to the topic “Power from an AC source,” later in this chapter. 
If you use an additional power supply other than the CRCXF, 
that power supply must be listed for fire alarm applications, must 
have ground fault detection disabled, and must have a circuit 
ground (circuit common) that is isolated from earth ground. 
Hardware configuration 
In this application, none of the CRC input circuits or relay 
contacts are used. The CRC simply reads the card and passes the 
command list request to the 3-SAC and CPU for processing. 
Since the CRC lock and input circuits are not used, you must 
provide dummy loads to maintain correct supervision currents. 
See the installation sheet for the correct load values. 
SDU programming 
The SDU programmer must create a command list for each 
combination of floors desired. 
ACDB operation 
The site security officer determines which floors should be 
accessible for an access level, and assigns the correct command 
list to the access granted event for that level. The site security 
officer also determines which cardholders belong to each access 
level.