Twlighting
Member
Hey There,
Banging my head against a wall trying to get 'some' response out of an RS-422 device. In this case it's an ultrasonic anemometer which will ultimately be connected to an AMX controller to provide windspeed/direction readings.
The anemometer is capable of full duplex 422 and half duplex 485 at various common baud rates, however it has no external means to configure these settings, they must be modified over whatever the current serial interface is. Being this was a used unit, it's not clear what the current settings are.
The AMX device has a number of configurable 422/485 ports, so I've spent the evening swapping around TX/RX, flipping polarity, and changing port speed settings with no success in receiving data. So I've turned to the DMM to start measuring voltages on the controller and anemometer.
I've found the controller TX is usually held around +/- 4V between TXA and TXB, and RXA and RXB are around +/-300mV. This seems correct. Performed a few loopback tests on the controller, ports are working as expected.
Interestingly the anemometer has 0V between TXA and TXB, and also 0V between RXA and RXB. I am able to measure about +373mV from RXA to Gnd and RXB to Gnd, and +9mV from TXA/B to Gnd. This voltage disappears when I disconnect power to the anemometer, so that leads me to believe it's at least turning on, though there are no LEDs or other indicators that is the case.
Any guess if this would this point to the connection being setup for RS-485? Or to some sort of a failure on the unit?
As far as the units themselves:
Anemometer: WindObserver II | Gill Instruments
Controller: https://www.avace.com/pdf/NXI_installation.pdf
Thanks for any insight,
-Griffin
Banging my head against a wall trying to get 'some' response out of an RS-422 device. In this case it's an ultrasonic anemometer which will ultimately be connected to an AMX controller to provide windspeed/direction readings.
The anemometer is capable of full duplex 422 and half duplex 485 at various common baud rates, however it has no external means to configure these settings, they must be modified over whatever the current serial interface is. Being this was a used unit, it's not clear what the current settings are.
The AMX device has a number of configurable 422/485 ports, so I've spent the evening swapping around TX/RX, flipping polarity, and changing port speed settings with no success in receiving data. So I've turned to the DMM to start measuring voltages on the controller and anemometer.
I've found the controller TX is usually held around +/- 4V between TXA and TXB, and RXA and RXB are around +/-300mV. This seems correct. Performed a few loopback tests on the controller, ports are working as expected.
Interestingly the anemometer has 0V between TXA and TXB, and also 0V between RXA and RXB. I am able to measure about +373mV from RXA to Gnd and RXB to Gnd, and +9mV from TXA/B to Gnd. This voltage disappears when I disconnect power to the anemometer, so that leads me to believe it's at least turning on, though there are no LEDs or other indicators that is the case.
Any guess if this would this point to the connection being setup for RS-485? Or to some sort of a failure on the unit?
As far as the units themselves:
Anemometer: WindObserver II | Gill Instruments
Controller: https://www.avace.com/pdf/NXI_installation.pdf
Thanks for any insight,
-Griffin