---
title: How to wire BACnet field bus for integrating 2 wire and 3 wire MSTP controllers
description: BACnet MSTP Controller suppliers offer either 2 wire or 3 wire field bus.
---

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# How to wire BACnet field bus for integrating 2 wire and 3 wire MSTP controllers

## BACnet MSTP Controller suppliers offer either 2 wire or 3 wire field bus.

BACNet has three wire BACNet Bus and Third party has three or two wire. Below is the configuration that should be followed :

1. Try to run two different MSTP Buses. ( one for 2-wire and one for 3-wire)
2. Not more than 30% third party devices are advised. Some two wire devices on three wire BACnet is allowed.
3. Some Controllers have built-in EOL resistors. 
4. On Niagara Network the BAUD Rate should be 38.400 for all devices. It should **not be set** to  Auto.

 

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