Article Author: Krista Kim

When connecting XPass D2 and CoreStation with RS-485 connection but using a separate power supply, please make sure that 485 TRXN(Yellow with black stripe), 485 TRXP(Blue with white stripe), and GND (Black with white stripe) of XPass D2 must be connected to CoreStation RS-485 port. XPass D2 GND is used for both power and RS-485 so there is a high chance that you may miss connecting XPass D2 GND to CoreStation when especially using separate power for XPass D2. Please check the following points to make sure to wire the proper method of RS-485. 

1)    Please check that RS-485 is daisy-chained in the correct way 

[Both BioStar] Daisy Chain and RS485 Connection

2)    Please check that XPass D2 GND connects to CoreStation 

3)   Please check that the terminating resistance switch of CoreStation must be always on and the termination resistor (120 Ohms) must connect to the ends of the daisy chain connection

4)    Please check if the wire consists of AWG24 twisted pair cable for RS-485. 

- 120-ohm register is recommended.