AB9900 - Reading information on BacNet Network



  1. We would like to read/write informations on a BacNet/IP Network (HVAC system) with a Modbus IP (or RTU) PLC (from Modbus to BacNEt/IP) .
    Is it possible with the AB9900 Gateway (Modbus to BacNet/IP) ?

  2. That would mean that communication would work on both direction ? BacNEtIP => Modbus IP and Modbus IP => BacNet ?

  3. How do we do this parametering ?

Thanks for your help

Best regards


Hello John,

I am not sure i have enough info here to say for sure but I am leaning towards this might not be the right device for you application.
The ab9900 is a modbus (rtu)slave/(tcp)client. From the modbus side it is going to be reading and writing data to modbus servers/slaves. From the BACnet side we are a server/Slave. So you are configuring backnet io points to be read or written to.

Here is a screen shot showing the default mapping we setup on the device. You are configuring modbus request and mapping them to backnet IO points.