Serial Tap Pro

The Answer to All Your Serial Needs

Price:

$495

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Serial Tap Pro is a high-performance hardware sniffer for RS232, RS485, and TTL-level UART communications, designed to meet the demands of advanced serial diagnostics.

Serial Tap Pro taps into both data and control lines and streams captured traffic to IO Ninja software in real time. In addition to all the great features of the original Serial Tap, such as RS232 line jumpers, convenient quick-release terminal block, and DB9 wedge-monitoring, the Serial Tap Pro supports 2Mbps+ baud rates, features electrically isolated serial interfaces, and allows users not only to monitor but also to drive serial lines (injection). It supports 9-bit data, and delivers microsecond-precision hardware timestamps for each byte, ensuring accurate timing analysis. With guaranteed byte-perfect sequencing, the Serial Tap Pro is the ultimate tool for engineers and developers who require reliable, high-fidelity serial communication analysis.

Why Serial Tap Pro is the Best Serial Solution on the Market

Electrical Isolation

Serial Tap Pro incorporates galvanic isolation across all of its serial inputs to ensure superior signal integrity and robust electrical protection, both for the host (PC) and the serial device. Galvanic isolation means that the USB is isolated from all the interfaces, preventing ground loops and protecting against voltage spikes. This design is critical in industrial and debugging environments where varying ground potentials or noisy power conditions can cause data corruption or damage the host. The isolation barriers sit between the transceivers (RS232, RS485/RS422, and UART) and the FPGA core, electrically separating monitored systems from the USB and internal logic domains.

High Baud Rates

Serial Tap Pro is built for high-performance serial analysis and supports significantly higher baud rates. The tap can operate at up to 2.5 Mbps for RS232 and TTL lines, and up to 2 Mbps for RS485. These speeds make it suitable for time-sensitive applications such as high-throughput data acquisition systems or automation interfaces.

Guaranteed Byte-Perfect Sequencing

Serial Tap Pro guarantees byte-perfect sequencing, ensuring that every captured event, whether it's a transmitted or received byte, a control line change, or even an error condition like a parity or framing error, is logged in the exact order it occurred. This precise ordering is critical for reliable analysis, as it maintains the true temporal and logical flow of serial communication. Notably, even error events are correctly positioned in the stream, appearing immediately after the problematic byte, which provides valuable insight during troubleshooting. This feature operates independently of, but in perfect complement to, Serial Tap Pro’s microsecond-precision hardware timestamps, together offering an unmatched level of detail and accuracy for high-fidelity serial diagnostics.

Microsecond-Precision Hardware Timestamps

Serial Tap Pro captures all serial events with microsecond-precision, including both byte transmissions and asynchronous line state changes, useful for debugging timing-sensitive issues. This level of accuracy allows devs to analyze inter-byte delays, protocol timing, and flow control transitions, and to correlate events across systems with exact timestamps. By preserving both the data and its context, the tap enables detailed reconstruction of sequences, which is essential for troubleshooting, validation, and embedded system development.

Support for 9-bit Data Frames

Serial Tap Pro supports 9-bit UART communication, used in some industrial systems to distinguish address from data frames. This helps slave devices in multipoint networks, like SCADA and controllers, ignore irrelevant traffic and save power. In IO Ninja, the 9th bit is shown with a red overline, making address bytes easy to spot during trace analysis.

RS485 Data Direction Detection

Serial Tap Pro features RS485 data direction detection, enabling you to precisely identify which device on a RS485 bus is transmitting at any given moment. In typical half-duplex RS485 configurations, all nodes share a single differential pair, which makes determining the origin of a message difficult. Serial Tap Pro addresses this by inserting itself in-line between two physical points on the RS485 bus. It connects to the differential pairs D1+/D1− and D2+/D2−. Acting as a transparent man-in-the-middle, its FPGA core actively forwards data between these two bus segments. This approach ensures that for every byte received, the FPGA knows whether it came from the D1 or D2 side, allowing it to infer the sender's direction without relying on protocol decoding or timing heuristics. Thanks to this method, RS485 data direction detection works at the physical layer, independent of the protocol being used in the session.

Packet Injection

Serial Tap Pro supports active packet injection (driving lines), enabling users to send custom serial packets and drive control lines on all interfaces, turning it into an all-in-one USB-to-serial adapter. This functionality is especially useful for simulation, fault injection, and response testing in complex serial systems.

Wedge RS232 Monitoring

You can insert Serial Tap Pro between two RS232 devices, effectively "wedging" it into the existing connection.

Passthrough

Serial Tap Pro also features serial passthrough for Wedge RS232 monitoring, meaning it maintains continuity of serial communication even when the device itself is powered off or disconnected from USB. This hardware-level design ensures that the tap does not interrupt or interfere with the flow of data between connected serial devices.

Analyzer Support

Serial Tap Pro is further enhanced with the addition of IO Ninja's analyzers, including for Modbus, BACnet, and DF1. These analyzers can be added or removed from any session and turn hard to decipher binary into human-readable packets.

Features

• USB-powered, no external power adapter required
• Three operating modes: RS232, RS485, and TTL-level UART
• Quick-release terminal block for easy wiring of TTL/RS485 signals
• Monitoring of all serial lines: TX, RX, RTS, CTS, DTR, DSR, DCD and RI
• Onboard line status LEDs for immediate visual feedback
• "Wedge" monitoring of RS232 communications:
  • DB9 connectors for placing the Tap "between" RS232 devices
  • Jumpers for swapping and loopbacking RS232 signals within TX/RX, RTS/CTS, and DTR/DSR signal pairs
  • Bi-color LEDs for distinguishing between positive, negative, and zero voltage levels on RS232 lines
• Real-time data streaming to IO Ninja software for live capture and analysis
• Electrically isolated serial interfaces (galvanic isolation)
• High-speed data support (up to 2.5 Mbps)
• Microsecond-precision hardware timestamps
• Support for 9-bit UART frames
• RS485 data direction detection (D1↔D2 forwarding)
• Packet injection (line driving) capabilities

Specifications

General

USB Interface

RS232 Interface

TTL Interface

RS485 Interface

The Serial Tap Pro contains no non-volatile memory and provides no means of connecting external storage devices. All captured data is streamed in real-time via USB to the host PC. The device does not retain any intercepted communications or user data, meaning it is suitable for use in environments with strict data security requirements.

OS Support

Serial Tap Pro is supported on Windows, MacOS and Linux operating systems.

Package Contents

• Serial Tap Pro
• USB-C cable
• Two DB9 gender changers
• Two hex screws (for female DB9)
• Three spare red jumpers

Documentation

Gallery