AQ-3-N in T3000 with RS-485 only connection

I have a brand new AQ-3-N that I’m trying to set up in T3000. I do not have a T3 controller. I connected a USB to RS-485 adapter to the PC that T3000 runs on. The RS-485 adapter is connected to the AQ-3-N. Is this even supposed to work or am I trying the impossible?

I tried “Add Modbus Device”, then selected “Com port” from the “Add Custom Device” pop-up window. I selected the COM port that corresponds to my RS-485 adapter and set the Modbus ID to 254 (this is the default according to the AQ-3-N manual). I tried all possible baudrates and all failed.

I have a sniffer connected to the RS-485 bus and I can confirm the software on the PC side (and the RS-485 hardware) seems to work as expected. When T3000 tries to discover the node, I can see a “Read Multiple Holding Registers” (function 3) message being sent to address 254. The message is sent 6 times, 5 seconds apart.

After experimenting for a little while, I noticed that the AQ-3-N sends a few bytes on the RS-485 bus after reset, at 57600 bps. Example:
1620529441.836423: 56 6e
1620529452.303102: 8f cd fe
1620529452.332410: cc dd cd ad 08 56 fe

I don’t know what to make out of this, but at least I know my RS-485 hardware is working as expected in both directions, since I can see data being sent by the sensor.

I have a brand new AQ-3-N that I’m trying to set up in T3000. I do not have a T3 controller. I connected a USB to RS-485 adapter to the PC that T3000 runs on. The RS-485 adapter is connected to the AQ-3-N. Is this even supposed to work or am I trying the impossible?

You don’t need the T3 controller, just the RS485 adapter is fine and yes that should be enough to get started.

I tried “Add Modbus Device”, then selected “Com port” from the “Add Custom Device” pop-up window.

Actually you just use the ‘Add device’ option when you are working offline.

I selected the COM port that corresponds to my RS-485 adapter and set the Modbus ID to 254 (this is the default according to the AQ-3-N manual). I tried all possible baud rates and all failed.

You now should hit the magnifying glass icon and the software should scan for devices. It will automatically run through all com ports at all baud rates using both Modbus and Bacnet protocols.

I have a sniffer connected to the RS-485 bus and I can confirm the software on the PC side (and the RS-485 hardware) seems to work as expected. When T3000 tries to discover the node, I can see a “Read Multiple Holding Registers” (function 3) message being sent to address 254. The message is sent 6 times, 5 seconds apart.

After experimenting for a little while, I noticed that the AQ-3-N sends a few bytes on the RS-485 bus after reset, at 57600 bps. Example:
1620529441.836423: 56 6e
1620529452.303102: 8f cd fe
1620529452.332410: cc dd cd ad 08 56 fe

I don’t know what to make out of this, but at least I know my RS-485 hardware is working as expected in both directions, since I can see data being sent by the sensor.

Awesome. Worked like a charm. Thanks!!