Atlona Help Center

KB01040 - AT-HDVS-200-TX cannot control display/projector via RS232


Scenario: The HDVS-200-TX cannot control a display/projector using RS232. 


  • You are using the AT-HDVS-200-RX, a compatible AT-UHD-CLSO switcher or are using a display/projector with HDBaseT inputs that support RS232 control (over HDBaseT). Related products found here:
  • You have confirmed the commands you have for controlling your display work as you can control your display locally through a computer or serial program.
  • You have checked the baud rate and port settings that are configured on the AT-HDVS-200-RX (or other HDBaseT receivers) web interface and they match the settings of your display. Default baud rate for RS232 outputs on the HDVS-200 system is 9600.


  • Check that firmware should be 1.0.45 for the HDVS-200-TX and 1.0.32 for the HDVS-200-RX (or subsequent future versions)
  • RS232 port 1 is used on the AT-HDVS-200-RX for RS232 communication with displays. RS232 port 2 is used for local control of the AT-HDVS-200-RX.
  • The RX pin on the Atlona RS232 port should go to the TX pin on the display. TX pin on the Atlona should go to the RX pin on the display. Ground to ground. You may need to refer to your displays/projectors user’s manual to find the RS232 pinout.
  • In the HDVS-200-TX web interface, under RS-232/IP commands page, confirm the commands are being sent via either HEX or ASCII and the appropriate communication method is chosen. Please note (Hex is typically denoted by octets (i.e. 02 B2 18) and ASCII is often written in as words or abbreviations (i.e. PWR ON))
  • It’s possible to have commands that are a mix of ASCII and HEX, Atlona recommends all commands converted to HEX (Atlona commands included). Free HEX to ASCII converter found here.
  • If a carriage return, line feed or another end of line symbol is required, select this next to each command in the appropriate drop down – Atlona supports: CR, LF, CR-LF, Space, STX, ETX, Null

(HDVS-200-TX Web-Interface RS232 Configuration page)

  • If using the Feedback Verify function, please note it will do the following: When turned on, and a command is written into the “feedback” section for RS232/IP commands, the Atlona system will attempt to send a command once every second until it receives the feedback specified in the web interface. If the Atlona unit doesn’t receive feedback after the first command is sent, it will resend the command up to another 2 times (for a total of 3 attempts). On the third attempt, if feedback is not received it will stop sending the command unless you request it.
  • Please also confirm the appropriate “Display Mode” setting has been selected to match your desired functions:

DispSW Avon: Display switches on/off, source audio/video signal always on

DispSW AVSW: Display switches on/off, source audio/video signal switches on/off

AV SW: Display is always on, source audio/video signal switches on/off

If you are still unable to get the display/projector to respond, let’s attempt to test the Atlona through a different method:

  • Using a PC or Mac with a USB to Serial cable, connect the output of the supported HDBaseT receiver (such as the AT-HDVS-200-RX) to the USB to Serial cable.
  • Make sure to confirm that the TX pin of the cable goes to the RX pin on the Atlona and vice versa for the RX pin of the cable and the TX pin on the Atlona.
  • Launch a serial program (such as this free one) and set your port settings to match those configured in the HDVS-200-TX web interface (matching the settings of your display/projector).
  • Log into the web interface of the AT-HDVS-200-TX and “Test” your ON/OFF commands to see if you are able to see these commands show up in your connection with the PC (The PC simulates your connection with a display/projector).
  • If this works, the Atlona units are then confirmed to pass commands and there is either an issue with the actual display control command being wrong, the port settings are incorrect or there is a cabling/hardware issue at the display.

If you are still unable to see the commands coming from the TX unit to the RX and PC, let's perform another test to verify the PC has communication with the Atlona AT-HDVS-200-RX:

  • Reestablish your RS232 connection between your PC and the AT-HDVS-200-RX
  • Change the baud rate of the connection between the Atlona and the PC to 115200 (to match the RX’s settings).
  • After the connection is established at 115200 baud, send the following command: “Version” (no quoted – case sensitive) to the AT-HDVS-200-RX followed by a carriage return.
  • You should see a response with the firmware version of the Atlona unit which confirms proper communication is established.
  • If you have confirmed communication between the Atlona HDVS-200-RX and the PC exists without issues, please check that the commands were properly stored in the AT-HDVS-200-TX web interface (if you did not press SAVE after entering commands, the codes may not have been stored).
  • If codes are confirmed to be programmed, please try controlling your display/projector directly again to see if you still have control over it. If control is lost, check with your display/projector manufacturer if there are any specific settings that need to be enabled to allow for RS232 control.

Article ID: KB01040

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