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Help a starter out with RS232?
This thread has 5 replies. Displaying all posts.
Post 1 made on Tuesday March 15, 2022 at 18:32
Junior Member
March 2022
So I recently got a Xantech HD44CC5 component video switcher. Didn't come with a remote, and to the bafflement of myself, has no buttons to control anything. I wanted to use it as a 4 in 1 out, but the default is a 4 out 1 in. It came with a little board to break the DB9 connector on the back into 5 pins, (GND, RX, TX, RTS and CTS)
I have been trying for weeks now to get this to work. I have had very limited success. I have installed like, 5 terminal programs, none of which seem to be super intuitive but maybe I'm the problem. anyway
The way I'm using to control it is an Arduino Uno board (technically a red board but I believe they're very very similar). I have 5v on ground, other ground going into that DB9 board i mentioned, and have tried rx-rx+tx-tx and rx-tx+tx-rx
Nothing has worked. I am at a loss. The drivers are installed, I can send commands (i think), the board has some response to the switcher flashing lights when it goes on and off, but no commands seem to be sent through.
I have 1byte hex codes (i think thats what they are) from Xantech's own universal dragon program, and they give some other wierd format in the manual
Tried em all, nothing works. If there's something here that you think might be the issue, let me know, I'm open to anything. Thanks a lot.
Post 2 made on Monday April 4, 2022 at 09:26
Long Time Member
January 2006
This site has a link to the HD44CC5 product manual. Product manual has the rs232 commands and syntax, as well as the pinout to the rs232 port. I haven't used this switcher before, but if you are having trouble with command structure or pinout maybe this will help?

Post 3 made on Tuesday June 21, 2022 at 11:44
Lurking Member
October 2008
I would start by getting Putty on a Windows PC and a USB to DB9 adapter for your computer and connecting it RIGHT to a computer to ensure you are sending the proper commands. Plenty of YouTube videos on how to use Putty for RS232 control out there.

You should use a straight through M/F DB9 cable (serial cable) from the PC to the Xantech unit. Open Putty, then start trying commands.

It does not look like you need to send a carriage return for the command to take, so that shouldn't be necessary. Just send a command and look for a response from the unit to your computer.

For example:


You should get a bunch of information back about the unit.

Make sure dip switches are in the proper position as dictated by the manual.
I would leave all four switches in the 'off' position.

If you want, you could pick up a IR remote on eBay, but they aren't really cheap...

Overall, while this is a interesting product, I would be more inclined to use a Extron Crosspoint RGBHV switcher w/audio as it can act similarly and has the front buttons along with very easy RS232 control. But, it doesn't extend over cat-5e if you need that.

Manual I looked at was here:
[Link:] - Custom AV Installation in the Washington DC area
Post 4 made on Wednesday July 20, 2022 at 11:22
Long Time Member
October 2005
Not familiar with that particular model but be warned that if the manual says it uses hex codes it can either mean they want the Ascii representation of the hex value or it may mean they want the actual hex value-

they are not the same.
Post 5 made on Sunday November 27, 2022 at 14:54
Junior Member
November 2022
Assuming we're on a computer that supports ASCII (or something similar) encoding: Uppercase letters are represented by hexadecimal values between 0x40 and 0x5A.
Post 6 made on Tuesday May 16, 2023 at 05:00
Junior Member
April 2023
Troubleshooting this kind of setup can be challenging, but let's try to identify potential issues and suggest some steps to resolve them:
  1. Double-check the wiring: Ensure that you have connected the Arduino Uno board to the DB9 board correctly. Verify that the connections for ground, RX, TX, RTS, and CTS are accurate. It's crucial to have the correct pin-to-pin connections to establish communication between the devices.
  2. Check the serial communication settings: Confirm that the baud rate, data bits, stop bits, and parity settings on both the Arduino Uno and the terminal program you're using match each other and the specifications of the Xantech switcher. The switcher's manual should provide information on the required settings.
  3. Verify the command format: Make sure you are sending the commands to the Xantech switcher in the correct format. If you have hex codes, you may need to convert them to the appropriate format required by the switcher. Double-check the switcher's manual or documentation to ensure you are using the correct command format.
  4. Test with a different terminal program: If you're having trouble with the terminal programs you've tried so far, consider experimenting with different terminal programs or serial communication libraries for Arduino. Some popular options for Arduino serial communication include Serial Monitor (built-in with the Arduino IDE), CoolTerm, and RealTerm.
  5. Test with a simple command: Start by sending a simple command to the switcher, such as switching the input to a known port. This can help verify if the communication is working as expected. Gradually add complexity to the commands once you establish basic functionality.
  6. Use an oscilloscope or logic analyzer: If you have access to an oscilloscope or logic analyzer, you can monitor the signals (RX, TX) to verify if data is being transmitted and received correctly. This can help identify potential issues with signal levels, timing, or data format.
Remember to handle the serial communication lines (RX and TX) with care to avoid damaging the Arduino or the Xantech switcher. Ensure that the voltage levels are compatible between the devices.

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