Proceed as follows:

  1. Enter the IP address from the router administrator page device list to access BACnet MSTP Configuration page and go to the BACnet Settings page.
  1. Switch your Surface Mount back to Mode 2 (DHCP mode).
  1. Select MS/TP and disable cloud connectivity.
  1. Click Save & Apply.

Configuration web page

  • Data Connectivity Settings page

RS-485 daisy chain

Daisy chain wiring

Using terminals A+ and B-, connect the in-wall mounts to the BACnet router (or other BACnet devices) in a daisy chain topology. Ensure that the power is shut off during wiring.

A+, B-

Twisted pair

120 Ohm

Bus terminating resistor (½ W 5 %) at BOTH ends

G

Reference wire

PTC

Special-thermistor (TRF250-120) at ONE end

Shield

Examples of recommended cable types

Capacitance

Shield 1)

Temperature

Pairs

39 pF/m
12 pF/ft

Foil + Braid

80 °C

1.5

41 pF/m
12.5 pF/ft

Foil + Braid

80 °C

2 2)

43 pF/m
13.1 pF/ft

Foil

80 °C

2 2)

Notes:

1) Foil + Braid is recommended for harsh environment (mechanical and electromagnetic interference, e.g. variable speed drives).

2) 2-pair cable to be used with care because of different color scheme.
The two conductors of the second pair must be wired in parallel to the reference terminal to prevent a floating conductor.