MOISTURE METERS AcuDew Dewpoint Transmitter

1 Introduction Modbus 1.1 What is Modbus Modbus is a digital communication protocol commonly used to enable communication between multiple electronic devices and a central controller, such as a programmable logic controller (PLC). It facilitates the transmission of signals and data from instrumentation or other control devices to a main controller or data acquisition system, as well as the transmission of control commands in the opposite direction. In the Modbus protocol, the device that initiates requests for information is known as the Modbus client, while the devices that respond to these...

2 Getting Started Before starting please check you have all the necessary components. If you do not have access to Modbus test software, please install it. The software is free and this guide will explain how to access it. 3 Equipment Required Please ensure you have the following components to set up your AcuDew Modbus RTU dewpoint transmitter. TRANSMITTER CABLE USB CONVERTER POWER SUPPLY 4 Downloading and Installing Modbus Test Software Access to Modbus software is necessary for testing the equipment; however, you do not require a specific version to do this. For this tutorial we will use GModbus,...

4.3 To download the Gmodbus zip file, select the option Modbus RTU/TCP tester (free) (Fig. 2). Download the Modbus file. 4.4 Right click and select Extract All (Fig. 3). 4.5 Open the folder titled GModbus and select the Application file (Fig. 4). 5 Connecting the Transmitter5.1 Equipment Set Up 5.1.1 Loosen the screw terminals in your converter, do not remove fully (Fig. 6). 5.1.2 Connect the wires to the screw terminals (Fig. 7and8). NOTE: If your USB to RS485 converter is different to the one in this tutorial please follow the wiring instructions as per your USB converter.

5.1.3 Connect the M12 screw collar to the transmitter (Fig. 9). 5.1.4 Connect the USB converter to the USB cable. 5.2 Connecting the Equipment to Your Computer 5.2.1 Open Device Manager on your PC. 5.2.2 Connect the USB cable to your PC and switch on the power supply. 5.2.3 Ports (COM & LPT) appear in the list. Click on Ports (COM & LPT) to find the COM number for USB-SERIAL CH340 (Fig. 10). Note the COM number. For this tutorial it is COM3. File Action View Help > Audio inputs and outputs > Human Interface Devices > (£ Mice and other pointing devices > £? Network adapters v J Ports (COM fit...

5.2.5 Click Connect to port. Click Read registers (Fig. 13). Once the correct port is selected, the following Fig. 14 data will appear on the right hand side of the screen (Fig. 14). This confirms the connections are correct and the transmitter is functional. To measure dewpoint in degrees Celsius change the read Modbus address from 3009 to 3001 and click 'Read registers' again. The '32bit value' column will display the dewpoint, measured by the transmitter, in degrees Celsius (Fig. 15). You can now integrate the transmitter into your system. 6 Troubleshooting Fig. 15 Error Message 7 Contact...

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