There seems to be tons of information out there as to how to connect up BACnet and implement Building Managent systems, but almost nothing about how to make a sensor to connect to it.
So, I‘d like to design a device that can supply half a dozen analogue parameters and a few on/off binary levels.
What I know so far is that each is called an “object”, the system controller sends a UDP datagram to the sensor, and the sensor responds by sending the data that was requested as another UDP datagram.
And also, that if a parameter strays outside a set band, the sensor sends that data without being asked.
I’m guessing that one of those USRiot modules can handle the UDP datagrams, and all I have to do is decode the serial data, and send the reply.
Have I hugely underestimated what is involved? Any pointers to useful application notes, microcontroller software examples etc. would be much appreciated.

 

Hi Ian0,
please provide a circuit when you are asking questions. BACnet is just a protocol. UDP is the complement of TCP, the protocol sends information but does not require a response from the opposite side that the information was received, unlike TCP which will not send more packets until it receives a confirmation.

If your module has a sensor and an MCU, the MCU reads the analog or digital data from the sensor and then sends it via UDP to a cental processing module, which handles your control.

I don't know why the name was changed from SmartHouse to a building management system, but it can be done very easily. The biggest problem is the regulatory and legal requirements and calling the police, which will require a connection to a phone line.

If by this "few on/off binary levels" you mean 1 for a switch on and 0 for a switch off, then this is possible. I suggest that you specify the MCU for this project(I will guess Arduino Mega 2560 or NodeMCU 8266). Processing analog sensors and digital switches is not a problem. For the analog sensors you have to learn how to use software filters.

 

Hi Ian0,
please provide a circuit when you are asking questions. BACnet is just a protocol. UDP is the complement of TCP, the protocol sends information but does not require a response from the opposite side that the information was received, unlike TCP which will not send more packets until it receives a confirmation.

If your module has a sensor and an MCU, the MCU reads the analog or digital data from the sensor and then sends it via UDP to a cental processing module, which handles your control.

I don't know why the name was changed from SmartHouse to a building management system, but it can be done very easily. The biggest problem is the regulatory and legal requirements and calling the police, which will require a connection to a phone line.

If by this "few on/off binary levels" you mean 1 for a switch on and 0 for a switch off, then this is possible. I suggest that you specify the MCU for this project(I will guess Arduino Mega 2560 or NodeMCU 8266). Processing analog sensors and digital switches is not a problem. For the analog sensors you have to learn how to use software filters.

I don't have a circuit. I'll not be designing the circuit until I have determined if I can implement the software. It won't look like much - just a microcontroller connected to some inputs via suitable resistive dividers, and a 3.3V linear power supply.
Most likely my choice of microprocessor will be the LPC1517.
From what I know of BACnet already, the sensor doesn't send any data until it is asked, unless a COV situation occurs.
The sensor does not connect to a telephone line. That is the job of the controller. I'm designing a sensor.
The sensors will be measuring mains voltage (via an isolating transformer), mains current (via a current transformer) and a few other parameters. The software squares the reading, filters it via a CIC filter with the comb centred on 100Hz to remove the ripple and then takes the square root via a quadratic approximation, to get the RMS value.