Title: Hardware Installation Guide.pdf
Open collector output is used by readers to send reader data DATA1/DATA0 (WD1/WD0) and to control external LEDs. Pull-up resistors and diode clamps are provided for reader data outputs. This type of interface is limited to 500 feet.1.4Relay OutputsSome Lenel hardware products provide form C relay contact outputs. These are dry contacts that are capable of switching signals as well as higher current loads. However, once they are used to switch current (for example, a door strike), they can not be used reliably to switch small signals (for example, dialer input.)1.5RS-485 Communication OverviewThe EIA RS-485 standard defines an electrical interface for multi-point communication on bus transmission lines. It allows high-speed data transfer over extended distance (4000 feet/1219 m.) The RS-485 interface20 — revision 6Hardware Installation Guide