Connect Air Flow Sensor (AFS-1000) through serial connection


I’m trying to connect to a Temco Air Flow Sensor (AFS-1000) through serial connection. Power is provided to the Air Flow Sensor with a power supply set to 18 V. This was attempted by connecting the RS-485 pins to an RS-485 to RS-232 converter, then using a RS-232 to USB converter connected to a Windows PC. Tried this with the T3000 program and QModMaster - no luck in either case.

  1. Is my connection scheme wrong in any way to inhibit communication?
  2. Does anyone happen to know the default parameters associated with this unit (e.g. Baud Rate, Modbus vs Bancet, etc.)?
  3. Is there something I am not considering?

Either way, thank you all for your time and your help.

Have a good rest of your day,
. James

  1. This connection scheme is not desirable, we have tested this RS485< >RS232<- >USB mode, it does not work.
    You can order a direct RS485 to USB converter.
    Like this:
  2. Default baud rate is 115200, protocol is modbus, default modbus address is 254.

If you use the correct cable, it should be easily scanned by the T3000.

Great insight, it would have taken a long time to troubleshoot this without your help. I had ordered a RS485 to Ethernet converter to see if maybe this would work better (has this been tested?). If not, I will then source a RS485 to USB converter.

The final configuration will plug straight into a data logger that has RS-232 ports for communication. Maybe this would work better (since it is not 2 converters hooked together)?

Either way, I will try a few things based on your suggestions and reply with the results for future reference.

Thanks for your help,
. James

The T3-Nano has some on board logging features, maybe you could try with that and log directly over RS485.

In our current system we have a data logger which collects readings from ~4 different instruments including an anemometer. We are hoping to integrate this device directly into the system without the need for an intermediate transducer, however this part is also very affordable so if we can’t get it to work directly this is another good option - thanks for the recommendation.

I tried to connect to the T3000 software using a computer that has a configured RS232 port using the same RS485 to RS232 converter as before but it is still timing out. Is there other documentation I could look over other than the 4 page manual on the webpage that might have more information on the default parameters and other pertinent information?

Either way, thank you for your help and your time with this project,
. James

We were able to get this connected using the RS485 to USB converter. Here was the configuration

  • T3000 program used for initial connection and testing
  • Powered by 24 VDC power supply
  • RS485+, RS485-, GND connected to converter
  • Baud Rate set to 115200
  • Modbus Address set to 255

We have 2 of these sensors and they both were successfully transmitting data. Thank you all for your help with this.

. James

Thanks for the update JH, we’re standing by to help if anything else comes up. Do update the firmware and T3000 itself when you have a chance. This can be done under T3000 → help → check for updates.