Title: Hardware Installation Guide.pdf
Before a device can be connected to the RS-485 communication line, it must be checked for ground fault. Uncorrected ground fault can damage all devices connected to the RS-485 communication line.To check if there is ground fault for a new unit, follow the steps below.1. Apply power to all devices already successfully connected to the RS-485 line.2. Power up the new unit, but DO NOT connect it to the RS-485 line.3. Connect the signal ground (SG) of the RS-485 line through a 10K limiting resistor.4. Measure the AC and DC voltage across the resistor. There should NOT be more than 1 volt across the resistor. Otherwise find and clear the fault.4. Measure the AC and DC voltage across the resistor. There should NOT be more than 1 volt across the resistor. Otherwise find and clear the fault.5. Connect the new unit to the RS-485 line if no ground fault is found.44 — revision 64Hardware Installation GuideMaintenanceFirmware download is only supported for models and versions of Lenel hardware.