GSI Modbus Test Pro

Our full featured version of GSI Modbus Test is a fast and simple utility for testing Modbus devices over wifi. It is similar to our free lite version but has many more features and capabilities including both TCP & UDP capability and a wide range of MODBUS functionality.

Just tap the Comm button for the communication setup page to enter the communication parameters for your device. Return to the main display view to send your poll and view the data.

The Comm Setup view allows a number of addressing, timing, and communication mode parameters to be configured - just tap on any yellow label for a description of that parameter.

The app supports MODBUS-TCP, MODBUS-RTU, and MODBUS-ASCII protocols. It also supports the GSI protocol which was developed in 1985 and was the first tank gauging protocol to use standard RS232 and RS485 serial data communication media. The app also features a User Data Mode that allows you to enter a complete poll string independent of any particular protocol. This allows transmission of special ASCII data polls or any MODBUS command that is not natively supported by the app.

The following MODBUS function codes are supported:
1 – Read Coils
2 – Read Discrete Inputs
3 – Read Holding Registers
4 – Read Input Registers
5 – Write Single Coil
6 – Write Single Register
15 – Write Multiple Coils
16 – Write Multiple Registers

Addresses must be entered in standard MODBUS format (0-65535). If you are accustomed to specifying your register addresses in "Modicon format", simply subtract 1 from the Modicon Address and delete the prefix number.

When you exit the Comm Setup page, simply tap the Start Poll button to send your poll command. If you turn the Continuous Poll switch on, the Start Poll button will change to a Stop Poll button while the poll is in progress.

If the connection is successful, the communication status window will show the raw byte strings that were transmitted and received. The received data will also be shown in tabular form. The app also keeps track of a number of communication statistics. Simply swipe left to bring up the Statistics view.

Your device must be on the same wifi network with the device that you want to test. Be sure to use the Settings app to configure your network settings before using the app or you will surely get socket connection errors.

A number of additional features are currently under development including the following: (Note that some of these enhanced features may require an In-App purchase).
✒ Ability to define templates with data descriptions and engineering units and register data formats
✒ Server capability in addition to the client mode of operation
✒ Data logging with ability to print or email results

Please send us your suggestions for new features and improvements. We especially want to hear about any bugs or problems that you might encounter. Your 5-star rating will also be appreciated.