Keyscan CA250B Technical Instructions page 32

Relay DIP Switches
Relay boards have DIP switches that may be set to "normal" or "reversed". Each relay has an LED that
indicates the relay status:
 Normal – LED on the circuit board is not illuminated when door is locked
 Reversed – LED on the circuit board is illuminated when door is locked
Relay output and DIP switch assignments are noted on the OCB-8 diagrams on the succeeding pages.
Keyscan access control units include diodes, Install diodes across all DC door strikes as shown in Figure 23 on
page 35. The cathode of the diode connects to the positive side of the strike at the door. The anode of the
diode connects to the common return wire.
Diodes must be installed for proper operation.
Fail Safe/Fail Secure Lock Devices
The power supply's positive output connects to the common door relay outputs, which are labeled on the relay
board.
For 'fail-safe' and 'fail-secure' door strikes, observe the following relay connections:
 'Fail-safe' – connect the positive terminal on the door strike to the 'normally closed' position on the relay
board. Connect the return wire to the common on the DC power supply via the metal enclosure's ground
lug
 'Fail-secure' – connect the positive terminal on the door strike to the 'normally open' position on the relay
board. Connect the return wire to the common on the DC power supply via the metal enclosure's ground
lug
Warning
Before securing any exit, please ensure all wiring to electrical door hardware conforms to federal, state,
provincial, or municipal fire regulations and building codes.
Keyscan Inc. – Technical Guide (PC109x - 04.15) 32