Using the TAC I/A BACnet WorkPlace Balance Tool to balance a VAV, when requesting the box drive to Maximum flow, get error Controller was temporarily busy. Please restart this balancing step message.

Issue

Using the TAC I/A BACnet WorkPlace Balance Tool to balance a VAV, when requesting the box drive to Maximum flow, get error "Controller was temporarily busy. Please restart this balancing step” message.

What does this mean and how to solve it?

Product Line

TAC I/A Series

Environment

BACnet  WorkPlace Flow Balance Tool

MNB-V1

MNB-V2

Cause

Multiple tools connected to the same VAV controller. 

Resolution

"Controller was temporarily busy. Please restart this balancing step” message means one of two things – One tool has control of the VAV while another is attempting to connect or the VAV is in the process of completing a balancing step while another balancing function is attempted.

Flow balancing should be  accomplished with a single tool connected to a VAV controller.