CAS Modbus Scanner is a free, lightweight utility developed by Chipkin Automation Systems that allows engineering professionals to quickly discover, test, and troubleshoot Modbus RTU and Modbus TCP devices. Whether you are commissioning a new industrial sensor, validating a programmable logic controller (PLC), or troubleshooting network communication errors, this utility simplifies data retrieval without requiring complex programming. Prerequisites and Software Installation
Before initiating the configuration process, ensure you have the correct hardware interfaces and software files prepared.
Download the Utility: Obtain the official executable directly from the Chipkin Automation Systems website. The software is portable and runs directly without a standard Windows installation wizard.
Hardware Connections: For Modbus RTU, connect your serial device to your computer using a high-quality RS-485 to USB converter. For Modbus TCP, connect your device to the same local area network (LAN) using an Ethernet cable.
Driver Verification: Open the Windows Device Manager and expand the Ports (COM & LPT) section. Verify that your USB-to-serial adapter is recognized and note the assigned COM port number (e.g., COM3). Step-by-Step Connection Setup
Configuring the software requires matching the connection parameters exactly to the physical settings of your target slave device. Configuring Modbus RTU (Serial) Launch the CAS Modbus Scanner utility. Click on the Add Connection button in the top toolbar. Select Serial as your connection type.
Select the correct COM Port discovered in your Device Manager.
Match the serial communication parameters exactly to your device datasheet: Baud Rate: Commonly 9600, 19200, or 38400. Data Bits: Typically 8.
Parity: Select None, Even, or Odd (Even is the Modbus standard default). Stop Bits: Usually 1 or 2. Configuring Modbus TCP (Ethernet) Click Add Connection in the toolbar. Select TCP as your connection type.
Enter the specific IP Address of your target Modbus slave device.
Input the Port number. The universal standard port for Modbus TCP is 502. Discovering Devices and Creating Requests
Once the primary connection path is active, you must define which network nodes and memory addresses you want to poll. Adding a Device (Slave ID)
Right-click your newly created connection in the left-hand tree view. Select Add Device.
Enter the Device ID (also known as the Slave ID or Station Address). For RTU, this is typically a number between 1 and 247. For TCP, this defaults to 1 or 255 but depends on the internal device configuration. Adding a Data Request
Right-click on the newly added device and select Add Request.
Select the specific Function Code based on the data you need to read: Function 01 (Read Coils): For digital outputs. Function 02 (Read Discrete Inputs): For digital inputs.
Function 03 (Read Holding Registers): For configuration parameters and analog outputs.
Function 04 (Read Input Registers): For read-only analog inputs and sensor data.
Enter the Offset (the starting register address). Note whether your device manual uses 0-based or 1-based indexing.
Enter the Length (the total number of sequential registers you wish to read). Executing Tests and Analyzing Data
With your connection, device, and requests defined, you can now poll the hardware to verify data integrity.
Single Poll: Click the Scan button once to send a single request frame and view the immediate response.
Continuous Polling: Check the Loop box to constantly refresh the data at a specified interval (e.g., every 1000 milliseconds) to monitor live process changes.
Data Representation: View the bottom data pane to see raw register values. You can right-click the values to change the display format between Unsigned Integer, Signed Integer, Hexadecimal, Binary, or Floating Point (which combines two 16-bit registers). Troubleshooting Common Connection Errors
If the scanner fails to retrieve data, look for these common industrial communication errors:
Timeout Error: The scanner sent a request, but nothing responded. Check physical wiring, verify the device has power, and ensure the Slave ID matches perfectly.
Illegal Data Address (Exception Code 02): The scanner requested a register range that does not exist on the device. Lower your request length or check the memory map in your product manual.
CRC Error (RTU Only): Data is being corrupted during transmission. Ensure your baud rate and parity settings match exactly, reduce cable length, or check for electrical noise near the RS-485 line. If you want to tailor this guide further, let me know: Do you need to include steps for writing data to registers?
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