CAS BACnet Explorer: Adjusting MSTP MaxMaster in 3 Steps
CAS BACnet Explorer (v1) – MS/TP Max Master Setting
This article explains how to modify the Max Master setting used by CAS BACnet Explorer version 1.x when communicating on a BACnet MS/TP network. The Max Master value defines the highest MAC address that will participate in token passing on the MS/TP segment.
Adjusting this parameter can improve MS/TP network performance in installations where the number of master devices is known. By limiting the token rotation range, unnecessary polling of unused addresses can be avoided.
Procedure to change the MS/TP Max Master value:
1) Open the settings file using a text editor (such as Notepad).
The settings file may be located in one of the following directories:
C:\Users\<username>\Documents\CAS BACnet Explorer\Settings.xml
C:\Users\<username>\Documents\CAS BACnet Explorer (beta)\Settings.xml
2) Locate the iMSTPNmaxMaster parameter within the XML file.
3) Change the value to a number between 1 and 254.
Note: The value 255 (0xFF) is reserved for broadcast addressing and
should not be used.
From the BACnet Specification:
This parameter represents the value of the Max_Master property of the node’s Device object. The value of Max_Master specifies the highest allowable address for master nodes. The value of Max_Master shall be less than or equal to 127. If Max_Master is not writable in a node, its value shall be 127.
Note: This article applies only to version 1.xx of the CAS BACnet Explorer. Later versions may store configuration parameters differently or manage MS/TP limits automatically.