Testing and simulating with BAC0

BAC0 is a powerful BAS test tool. With it you can easily build tests scripts, and by using its assert syntax, you can make your DDC code stronger.

Using Assert and other commands

Let’s say your BAC controller sequence of operation is really simple. Something like this:

System stopped:
    When system is stopped, fan must be off,
    dampers must be closed, heater cannot operate.

System started:
    When system starts, fan command will be on.
    Dampers will open to minimum position.
    If fan status turns on, heating sequence will start.

And so on…

How would I test that ?

  • Controller is defined and its variable name is mycontroller
  • fan command = SF-C
  • Fan Status = SF-S
  • Dampers command = MAD-O
  • Heater = RH-O
  • Occupancy command = OCC-SCHEDULE

System Stopped Test Code:

mycontroller['OCC-SCHEDULE'] = Unoccupied
assert mycontroller['SF-C'] == False
assert mycontroller['MAD-O'] == 0
assert mycontroller['RH-O'] == 0

# Simulate fan status as SF-C is Off
mycontroller['SF-S'] = 'Off'

Sytstem Started Test Code:

mycontroller['OCC-SCHEDULE'] = 'Occupied'
assert mycontroller['SF-C'] == 'On'
# Give status
mycontroller['SF-S'] = 'On'
assert mycontroller['MAD-O'] == mycontroller['MADMIN-POS']

And so on…

You can define any test you want. As complex as you want. You will use more precise conditions instead of a simple time.sleep() function - most likely you will read a point value that tells you when the actual mode is active.

You can then add tests for the various temperature ranges; and build functions to simulate discharge air temperature depending on the heating or cooling stages… it’s all up to you!

Using tasks to automate simulation


Let’s say you want to poll a point every 5 seconds to see how the point reacted.:

Note: by default, polling is enabled on all points at a 10 second frequency. But you could

define a controller without polling and do specific point polling.:

mycontroller = BAC0.device(‘2:5’,5,bacnet,poll=0) mycontroller[‘point_name’].poll(delay=5)


Let’s say you want to automatically match the status of a point with it’s command to find times when it is reacting to conditions other than what you expected.:


Custom function

You could also define a complex function, and send that to the controller. This way, you’ll be able to continue using all synchronous functions of Jupyter Notebook for example. (technically, a large function will block any inputs until it’s finished)




import time

def test_Vernier():
    for each in range(0,101):
        controller['Vernier Sim'] = each
        print('Sending : %2f' % each)


This function updates the variable named “Vernier Sim” each 30 seconds; incrementing by 1 percent. This will take a really long time to finish. So instead, use the “do” method, and the function will be run is a separate thread so you are free to continue working on the device, while the function commands the controller’s point.