Serial TapI2C/SPI TapEthernet Tap

IO Ninja Serial Tap

The Serial Tap is an affordable sniffer for monitoring RS232, RS485, and TTL-level UART communications. The sniffer taps into the data and control lines of serial links and sends the recorded data to IO Ninja software in real time.

All inputs of the serial tap are available on a quick-release terminal block. The Tap also features two DB9 connectors for "wedge" monitoring of RS232 communications. The board even provides jumpers for swapping and loopbacking RS232 signals, and also sports bi-color LEDs for RS232 line status indication. The jumpers and bi-color LEDs give the Tap additional use as a simple tool for debugging RS232 wiring issues.

The Serial Tap must be used with the Serial Tap plugin of IO Ninja software.

Key Features

  • Designed for use with IO Ninja software (
  • Monitors TX, RX, RTS, CTS, DTR, and DSR lines of serial ports.
  • All inputs are connected to an 18-position, quick-release terminal block.
  • RS232, RS485, and UART (TTL) modes, selectable via a slide switch:
  • RS232 mode:
    • Two onboard DB9 connectors offer true "cable wedge" sniffing;
    • Six jumpers for swapping and loopbacking signals;
    • Six bi-color LEDs indicate the status of monitored RS232 lines;
    • DB9 connectors additionally pass through DCD and RI signals.
  • RS485 mode allows to monitor TX and RX signal pairs.
  • UART (TTL) mode allows to monitor UARTs of IC chips (1.8-5V logic).
  • Six yellow LEDs indicate the state of six monitored lines.
  • Full-speed (12Mbps) USB2.0 interface on a USB-C connector.
  • USB-powered, no additional external power necessary.
  • Supplied with a USB-C cable and two DB9 gender changers.
  • Compact, outside dimensions only 82 x 74 x 30 mm.


Hardware Manual (HTML)IO Ninja Hardware Manual in HTML format.
Hardware Manual (PDF)This is a PDF version of the IO Ninja Hardware Manual for downloading and printing.

Order the Serial Tap

Purchase this product from the IO Ninja web site*.

* is owned and operated by Tibbo Technology Inc.

Serial TapI2C/SPI TapEthernet Tap