Listen in
Tap a live line between master and outstation, serial or TCP, and watch both sides decoded field by field, with hardware timestamps and response times.
Meet Earwig
Hear what your RTUs are really saying.
Earwig is a SCADA protocol test set: a pocket-sized USB adapter and a desktop app that listen to, poll and impersonate DNP3, IEC 60870-5 and Modbus devices.
Three jobs, one bug
Listen in. Ask around. Play pretend.
Ask around
Be the master: integrity polls, interrogations, controls with select-before-operate, time sync, raw frames. Repeat anything on a timer and see what breaks.
Play pretend
Be the RTU: a simulated device with a live point database, events and unsolicited reports, so you can test the master before the field gear arrives.
The app
Every byte, decoded.
Click any message to see it field by field, next to the raw bytes. Filter, search, and stop the capture the moment something goes wrong.
⚡ Forced errors
Break things on purpose
Send bad CRCs, wrong addresses, sequence errors and malformed objects to see how devices cope.
⏱ Timing
Microsecond timestamps
The adapter stamps every byte in hardware, so gaps and turnaround times are measured, not guessed.
∿ Line analyzer
See the wire itself
Capture RXD, TXD, RTS, CTS and DCD edges and measure them with cursors, like a pocket logic analyzer.
✓ Test scripts
Repeatable test runs
Script a sequence with pass/fail checks, run it from the app or the command line, and get an HTML report.
⇄ Wireshark
Plays well with others
Export captures as pcap for Wireshark, or import Wireshark captures to decode them here.
⚑ Triggers
Catch the one bad frame
Stop on an error or on matching text, and log every event to a file for the overnight soak test.
Speaks fluent SCADA
The protocols your substations actually run.
Each one monitors, masters and simulates, written from scratch so a test set can send the malformed frames a normal stack won't.
DNP3
Link, transport and application layers, events, select-before-operate, unsolicited reporting.
SerialTCPTLS
IEC 60870-5-104
APCI with I, S and U frames, interrogations, commands, clock sync.
TCPTLS
IEC 60870-5-101
FT1.2 framing with the full ASDU set, polled or peer-to-peer.
UnbalancedBalanced
IEC 60870-5-103
Protection relays: messages, measurands, general commands and identification.
Serial
Modbus
All the common function codes, as client, server or silent observer.
RTUASCIITCP
Legacy bit protocols
Conitel 2020, CDC Type I/II and other vintage formats. On the bench.
Coming
The hardware
Small box. Real serial ports.
USB-to-serial cables don't do timing. Earwig's adapter has its own microcontroller, so the timing-critical parts happen in hardware.
- Ports2 × RS-232 on DB9, with RTS, CTS, DTR and DCD on each
- TimingMicrosecond hardware timestamps; gap-framed receive; scheduled transmit
- Radios & modemsRTS keying with lead and lag, wait-for-CTS, DCD-gated receive
- Sync linesReceive and transmit clock lines for synchronous links
- MonitorBoth ports listen at once, one per side of the line
- PowerUSB-C, bus-powered. Nothing else to carry.
- UpdatesSigned firmware updates from inside the app
- Size75 × 47 × 23 mm
On the bench
Earwig is the first instrument. There will be more.
Wren Instruments makes test gear for people who fix things: honest specs, fair prices, no nonsense.
Logic analyzer
Many channels, protocol decoders, and the same app you already know.
Oscilloscope
A small, sharp USB scope for the field kit.
More protocol testers
Fieldbus and serial protocols beyond SCADA. Tell us what you need.
Early access
Want an Earwig on your bench?
We're building the first batch now. Tell us what you test (protocols, links, the gear in the field) and we'll put you on the list.
Email hello@wreninstruments.com