PR602LCD Installation guide Rev.J.doc
3.5 Communication with controller
RS485 bus and UT communication interface (e.g. UT-2USB) are used for communication with
controller. Single RS485 bus creates network (subsystem) and up to 32 controllers with unique
addresses in range of 00..99 can be connected to the bus. For the communication with distant
subsystems it is required to use UT-4DR or UT-4 v2.0 communication interface or CPR32-NET
network controller as all of them enable communication through computer network (LAN or WAN).
The RS485 bus consists of two signal lines A and B. In the RACS 4 system any topology can be
used (star, tree or any combination of them, except for loop) in order to connect controllers in
network (subsystem). The matching resistors (terminators) connected at the ends of transmitting
lines are not required. In most cases communication works with any cable type (standard telephone
cable, shielded or unshielded twisted pair etc.) but the recommended cable is unshielded twisted
pair (U/UTP cat.5). Shielded cables should be limited to installations subject to strong
electromagnetic interferences. The RS485 communication standard used in the RACS 4 system
guarantees proper communication in a distance of up to 1200 meters as well as high resistance to
interferences.
3.6 Communication of controller with peripheral devices
The communication of controller and peripheral devices can be established by means of RACS
CLK/DTA, Wiegand or Magstripe bus. RACS CLK/DTA is the addressable bidirectional communication
standard developed by Roger company. Addresses of all devices connected to CLK and DTA lines
must be properly configured in range of 0..15. Factory default address of peripheral devices can be
changed according to procedures specified in their manuals but in majority of cases it is not
necessary to modify the addresses at all. Standard unshielded signal cables (e.g. U/UTP cat. 5) with
maximal length of 150m can be used for RACS CLK/DTA communication. Practically, devices
communicating on RACS CLK/DTA bus can be connected to the controller in distance up to 500m,
but such conditions are not guaranteed by the manufacturer. Wiegand and Magstripe
communication standards are commonly used in access control industry but their offer less
functionalities than RACS CLK/DTA standard.
3.6.1 PRT reader, XM expanders and HRT82FK panel (RACS CLK/DTA)
PR602LCD type controller is equipped with built-in reader and can operate with external PRT series
reader, XM-2 I/O expander, up to four XM-8 expanders dedicated to access control in elevators and
HRT82FK function key panel –see fig. 3. The address of PRT reader must be ID=0 (i.e. default
address), the address of XM-2 expander must be ID=5, addresses of XM-8 expanders must be in
range of ID=8..11 and the address of HRT82FK must be ID=12. All mentioned devices must be
connected to CLK and DTA lines of the controller.
