How to T3-OEM Bacnet Programmable Controller to control VAV through Bacnet MS/TP
Just add a program like any other application. if you put the io list and a rough sequence I can do an example program for you right here in the forum.
Here I will use a T3-LB as a device to demonstrate based on the information you showed.
Fill in the 4 CO2 sensors as analog inputs with the names and ranges you need.
In the OUTPUT interface, one digital output port is used as AHU, and one analog output port is used as VFD.
In the schedules interface, fill in the switch time as shown below.
In the program interface, write as shown below.
10001~10004 in the program are the Instance parameters in the valve Bacnet. AO1~AO4 are the corresponding output ports of the valve.
Thank you for the response,
Find the attached BACnet paratemeters for Belimo VAV,hope the program will match the same.
PICS ZE.pdf (566.5 KB)
Ljun’s VFD program needs a little work, during the day the speed should modulate from 50% on up to 80% as the Co2 level rises from the background level of 400ppm (for now) of fresh outside air and 1000 ppm for periods of high occupancy.
Conjuring up some grade school math the formula is worked out from the rise and the run and the b intercept as shown below.
Line 20 modulates the fan speed from 50% up to 80% as the maximum Co2 of the four rooms rises from 400 ppm up to 1000 ppm. Line 30 clips the fan speed between 50% and 80%. Finally in line 40 the speed will be at zero when the AHU is off.
05 IF SCH1 THEN START AHU ELSE STOP AHU
10 MAXCO2 = MAX ( IN1 , IN2, IN3, IN4 )
20 VFD = 0.05 * MAXCO2 + 30
30 VFD = MAX( 50 , MIN( 80 , VFD ) )
40 IF NOT AHU THEN VFD = 0