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Communicating by ASCII over a Serial Terminal

A guide to communicating with your device over a RS-232 serial terminal.

One of the benefits of the Gemini and Nova modules is their ability to communicate in ASCII via a Serial terminal. Useful for debugging and development, ASCII mode allows quick entry of basic SkyeTek API commands directly into a reader without any programming overhead. This guide will help you set up a basic software terminal for communicating to your module. For a more in-depth explanations and an explanation of all error codes and commands, please read the SkyeTek API Guide.

Getting Started

In order to communicate with your module via serial, your PC requires a software terminal emulator for sending data. We use Termite to emulate a terminal, but any standard terminal software should work.

Also, be sure your device and software are successfully configured by following this guide: Communicating with your Gemini / Nova

Using the Terminal

At this point, the terminal should have matching settings as the Nova. From here, we should be able to communicate with the device. Each command is surrounded by the carriage return character <CR>, with an optional CRC postfix (for this example we won’t be using it).

Important: Be sure your terminal software has the “Append <CR>” option selected!

Now, we need to test our terminal. In the input window, hit the “Enter” or “Return” key twice. Your module should then respond with:


This indicates your module can hear your PC, and is the standard Invalid Command response. Now, we should be able to grab the firmware version.

Hit the “Enter” key, write the following sequence in ASCII, then hit “Enter” again (because we have to surround each command with a <CR>):


This should result in a successful response:


This indicates you have a firmware version 01010002

From here, you should have full serial communication capabilities with your device. Some things to know about ASCII Mode:

  • ASCII mode uses double the bits as Binary mode, and may be slower.
  • ASCII mode does not require the start flag, and should not be included.
  • ASCII mode has optional CRC checks
    • Flag 0020 indicates the last additional 4 bytes contain the command CRC
    • Flag 0000 indicates no CRC is present in the command.

For more info on Error Codes, Reader Commands, and general program flow, please view the SkyeTek API Guide.

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