Overview
This application note explains how to download and use common terminal emulator applications referenced in Siretta documentation, including HyperTerminal, Tera Term and RealTerm.Terminal emulator software is commonly used to communicate with modems, routers, cellular modules and industrial devices over serial, USB serial, Telnet or TCP/IP connections.
This guide is not intended to replace the official user manual for each software package. Instead, it provides a basic getting started guide for customers who need to open a terminal session, configure the correct communication settings and begin sending commands to a Siretta device.
| Product Type | Relevance |
|---|---|
| Cellular Modems | Terminal emulators are commonly used to send AT commands, check modem responses and configure modem behaviour. |
| Industrial Routers | Terminal access may be used for diagnostics, serial testing, command entry or configuration support. |
| Embedded Cellular Modules | Terminal software can be used to test serial communication and confirm command responses during development. |
| Serial and USB Serial Devices | Terminal emulators provide a simple way to open COM ports, set baud rates and monitor transmitted or received data. |
| Ethernet and TCP/IP Devices | Some terminal tools can also connect using Telnet, raw TCP or other network-based terminal sessions. |
This application note explains:
Expected Result
At the end of this guide, the reader should understand how to download a suitable terminal emulator, connect to a Siretta device and begin basic serial or terminal communication.
A terminal emulator is a software application that allows a computer to communicate with another device using a text-based interface.
In Siretta documentation, terminal emulators are often used to communicate with devices using:
For many modem applications, the terminal emulator acts as a simple communication window.
The user types a command, sends it to the device, and reads the response returned by the device.
For example:
AT
OK
This confirms that the terminal emulator is communicating with the modem and that the modem is responding correctly.
Siretta documentation may refer to several terminal emulator applications. Each can be useful, but they are slightly different.
| Software | Typical Use | Key Strength | Best Suited For |
|---|---|---|---|
| HyperTerminal | Basic serial and terminal communication. | Simple interface and historically common in older Windows documentation. | Users following older guides or familiar with classic Windows terminal tools. |
| Tera Term | Serial, Telnet and SSH terminal sessions. | Free open-source terminal emulator with a clean interface and macro support. | General AT command testing and everyday serial communication. |
| RealTerm | Serial, TCP and binary data testing. | Advanced monitoring, capture and binary/hex display features. | More technical testing, diagnostics and low-level serial analysis. |
The following links were checked when this application note was prepared. Because terminal emulator software is maintained by third-party providers, download pages and version numbers may change over time.
| Software | Referenced Version | Download Link | Help / Manual Link |
|---|---|---|---|
| HyperTerminal Private Edition | Vendor download page; version may change | Download HyperTerminal Private Edition trial | HyperTerminal installation guide |
| Tera Term | Tera Term 5.6.2 / TTSSH 3.6.2, referenced release checked July 2026 | Tera Term GitHub releases | Tera Term 5 manual |
| RealTerm | RealTerm 2.0.0.70, referenced stable installer | RealTerm SourceForge files | RealTerm manual / documentation website |
Important Note
Siretta does not develop, support or maintain HyperTerminal, Tera Term or RealTerm and is not responsible for their use. These are third-party software applications, so users should download them only from the official vendor, project or recognised project-hosting pages.
For most basic Siretta modem testing, the simplest requirement is to open a serial COM port and send AT commands.
| Requirement | Suggested Tool | Reason |
|---|---|---|
| Basic AT command testing | Tera Term | Simple, commonly used and suitable for most serial terminal tasks. |
| Following older documentation that references HyperTerminal | HyperTerminal | Matches the terminology and screenshots used in some older guides. |
| Capturing serial data to a file | Tera Term or RealTerm | Both can be used for logging, depending on the level of detail required. |
| Viewing binary or hexadecimal data | RealTerm | RealTerm is better suited to low-level serial diagnostics. |
| Telnet, SSH or TCP/IP terminal access | Tera Term or RealTerm | Tool choice depends on the connection type and required features. |
Before opening a terminal session, confirm the communication settings required by the device.
Typical serial settings include:
| Setting | Typical Value | Description |
|---|---|---|
| Port | COM port assigned by Windows | The serial or USB serial port connected to the device. |
| Baud rate | Often 9600 or 115200 | The communication speed. Always check the product documentation. |
| Data bits | 8 | The number of data bits used in each serial frame. |
| Parity | None | Error checking bit setting. Many modem interfaces use no parity. |
| Stop bits | 1 | The number of stop bits used to indicate the end of each serial frame. |
| Flow control | None, RTS/CTS or Hardware | Depends on the device and cable. Check the relevant Siretta documentation. |
A common default format is often written as:
115200, 8, N, 1
This means:
Important Note
Do not assume every Siretta product uses the same baud rate or flow control setting. Always check the relevant product manual, application note or AT command guide.
Once connected, send a basic AT command.
AT
A working modem connection should normally respond with:
OK
If no response is received, check:
Tera Term can be downloaded from the Tera Term Open Source Project or from the project’s GitHub release page. :contentReference[oaicite:3]
AT.OK.| Feature | Use |
|---|---|
| Serial connection | Connect to a modem, router, module or serial device using a COM port. |
| Telnet / SSH | Connect to network devices using supported network terminal protocols. |
| Logging | Save terminal output to a text file for later review. |
| Macros | Automate repeated command sequences or test routines. |
| Local echo | Show typed characters locally if the connected device does not echo commands back. |
HyperTerminal Private Edition is available from Hilgraeve for modern Windows versions, including Windows 7, 8, 10 and 11. :contentReference[oaicite:4]
AT.OK.| Feature | Use |
|---|---|
| Simple serial terminal | Useful for basic command entry and response checking. |
| Connection profiles | Save common connection settings for later reuse. |
| Text capture | Capture session output where supported by the software version. |
| Familiar interface | Useful where older documentation or user experience already references HyperTerminal. |
Practical Note
HyperTerminal was historically included with older versions of Microsoft Windows, which is why it appears in many older modem and serial communication guides. For modern Windows installations, customers should use the current Hilgraeve version or select an alternative terminal emulator such as Tera Term or RealTerm.
RealTerm can be downloaded from the RealTerm website or SourceForge project page. :contentReference[oaicite:5]
AT.OK.| Feature | Use |
|---|---|
| Serial terminal | Connect to COM ports and serial devices. |
| Hex and binary display | Useful when viewing non-printable characters or binary data. |
| Capture to file | Record received data for diagnostics or support cases. |
| Send tab | Send specific strings, commands or byte sequences. |
| TCP connections | Useful for some network-based serial or socket testing scenarios. |
Practical Note
RealTerm is powerful, but it can be less intuitive for first-time users. It is often best used when more detailed serial diagnostics are required, such as checking line endings, binary output, capture files or low-level communication behaviour.
Some devices require a specific line ending before they respond to a command.
Common options include:
| Line Ending | Meaning | Typical Use |
|---|---|---|
| CR | Carriage Return | Commonly required by modem AT command interfaces. |
| LF | Line Feed | Used by some systems to indicate a new line. |
| CR + LF | Carriage Return and Line Feed | Often used where both command termination and readable formatting are required. |
If commands do not appear on screen while typing, local echo may be disabled.
This does not always mean the command is not being sent.
Try enabling local echo in the terminal emulator or check whether the connected device echoes received commands.
| Problem | Likely Cause | Suggested Check |
|---|---|---|
| No response to AT | Wrong COM port, wrong baud rate or device not powered. | Check Device Manager, power supply, cable and serial settings. |
| Garbled characters | Incorrect baud rate, parity or data format. | Confirm the correct serial settings from the product documentation. |
| Cannot open COM port | Port already in use or driver not installed. | Close other software and check the USB serial driver. |
| Commands type but nothing happens | Incorrect line ending or flow control. | Check CR/LF settings and flow control configuration. |
| Typed characters are not visible | Local echo disabled or device does not echo commands. | Enable local echo or send a test command and check for a response. |
| Unexpected command responses | Wrong command mode or device state. | Check the product manual and confirm whether the device is ready to accept commands. |
When using terminal emulator software with Siretta products:
AT command test.Terminal emulator software provides a simple way to communicate with Siretta modems, routers, modules and serial devices.
HyperTerminal, Tera Term and RealTerm can all be used for basic terminal communication, but they are not identical. Tera Term is often suitable for general AT command testing, HyperTerminal may be useful when following older documentation, and RealTerm is better suited to detailed serial diagnostics or binary data analysis.
For most users, the key steps are to download a suitable terminal emulator, select the correct COM port, configure the serial settings and send a basic AT command to confirm communication.
The terminal emulator’s official documentation should be used for full software-specific instructions, but this guide provides the basic starting point needed to begin working with Siretta devices.