BACnet Questions

PAC Project
1

I’ve been given a project to get Opto22 PAC Controllers talking to BACnet equipment. I’m slowly learning BACnet. I downloaded the Opto22 BACnet/IP integration kit and didn’t have much luck getting it to work with my initial setup which includes a an Opto22 PAC R2, a Fieldserver router and a Johnson Controls stat. I then noticed the code submitted by Nick Stephens a few years ago and downloaded that to give it a try. He had posted two subroutines, one for discovery and one for reading multiple points. I got the discovery subroutine to work although its a little odd. It will discovery 5 of 19 points very quickly but it will take a couple of minutes for the rest of the points to be discovered. The read operation still doesn’t work. I converted the read subroutine back to a chart last week and seem to get the same results as with the subroutine regardless of various small changes. So I fired up Wireshark to look at the packets being generated. Every TransmitString command seems to result in two similar but slightly different packets. I also get replies to both packets. On the discovery packets I can see the points coming back. I am not seeing any errors from the charts or subroutines.

So two questions:

  1. Can anyone tell me why I am getting two packets for every TransmitString command?
  2. Anyone with any further tips regarding BACnet on Opto22 hardware?
2

PhilH,

BACnet can be a bit tricky to integrate but I have had some success with it. I actually created my own subroutines to read/write to a device. I cannot answer the specific question about Nick’s subroutines but I know a few people have used them with success.

Are you attempting to make a PAC controller a device in a BACnet ecosystem? Or are you just trying to read/write data to a BACnet device? I can try to help either way. Feel free to respond here or contact me at korman@opto22.com.

3

I have had issues in this arena as well. I wonder has there been any consideration for a Opto22
controller that could speak BACnet natively.

4

CodeSys has a BACnet library. I am just starting a new project that will be using it. I’ve only gotten as far as to download the library into my project. It appears to be included at no additional cost and looks full featured.