Modbus Terminal

Modbus Terminal turns your Android phone into a Modbus master for testing, commissioning and troubleshooting PLCs, inverters, energy meters, sensors and any other Modbus slave.

Connect over Wi-Fi/Ethernet with Modbus TCP, or directly to the RS-485/RS-232 bus with Modbus RTU through a USB-serial adapter (USB OTG).

★ MAIN FEATURES
• Modbus TCP client (MBAP header) and Modbus RTU over USB serial (CRC16)
• All the common function codes:
01 Read Coils · 02 Read Discrete Inputs · 03 Read Holding Registers · 04 Read Input Registers
05 Write Single Coil · 06 Write Single Register · 0F Write Multiple Coils · 10 Write Multiple Registers
16 Mask Write Register · 17 Read/Write Multiple Registers
• Values in decimal (unsigned) or hexadecimal
• Two views: raw frame console, or a table with the address of every register and coil
• Modbus exceptions decoded by name (ILLEGAL DATA ADDRESS, SLAVE DEVICE FAILURE, …)
• Timeouts and incomplete responses reported clearly, even when the slave does not answer
• Requests checked before sending: unit id, address range, quantity and value limits of the specification
• Console with time, date or timestamp, and log recording to a text file
• The connection stays open in the background
• Light and dark theme

★ MODBUS RTU (USB SERIAL)
Supports USB-serial adapters with FTDI, Prolific PL2303 and CH340/CH341 chips and USB CDC-ACM devices. Baud rate from 1200 to 921600, 7/8 data bits, parity None/Odd/Even/Mark/Space, 1/1.5/2 stop bits. Your phone must support USB OTG.

★ NO ADVERTISING
Connection, reading, writing, console and logs are free for everyone, with no ads.
Cyclic send (automatic polling of a request every 100–2000 ms) is unlocked by an optional one-time in-app purchase, which also supports the development of the app. It is not a subscription.

Suggestions and bug reports are welcome: edodm.project@gmail.com