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On this page
First check whether your fault has its own page, such as Gateway does not come online or Modbus device shows no values. Each page lists how to check every cause. If that does not solve it, contact support.
Collect the details
Send the serial number of the gateway with every question. It is on the gateway page under the name of the gateway. Clicking the number copies it.
The table shows what else helps support, by type of question.
| Situation | Also send |
|---|---|
| Gateway does not come online or is offline | The status on the gateway page, since when it has been like this and a photo of the connections |
| Modbus device on RS485 shows no values | Brand and type, slave address, baud rate, parity and a photo of the wiring at the gateway and at the Modbus device |
| Modbus TCP device shows no values | Brand and type, IP address, port and unit ID |
| Values are wrong | The name of the register, the value in the portal, the value on the display of the Modbus device and the register map from the manual |
| Controlling a register fails | The message in the window and the value you wanted to write |
| Question about an API request | The X-Request-Id from the response and the time of the request |
| Message in the portal | A screenshot of the message and the page on which it appeared |
For RS485, give both the settings on the Modbus device itself and those under Modbus RTU-bus (Modbus RTU bus) in Gateway settings. If you tested on site with ModbusCloud Diagnostics, paste the text of the diagnostic report into your question. How to make that report is described in Find faults with the Diagnostics tab and the console.
Never send your password or an API key.
Contact support
You can reach support by email, phone and WhatsApp. The email address and the number are on the support page. Support also helps with setting up a Modbus device, such as the baud rate and the slave address. This is possible in Dutch, English and German.
If you are at the installation, call, or send a photo of the connections through WhatsApp.
Send feedback from the portal
With the feedback button you send a question or a fault from the portal, with a screenshot attached. The button is only available on a computer. On a phone or in a narrow window it is missing.
Open feedback
Click the round button with a speech bubble and a plus sign. It is at the bottom right of the screen, unless you moved it earlier. The Feedback window opens.
Choose the type of message
Choose Bug if something goes wrong, or Question if you want to know something. Idea is selected by default.
Write the message
In the text field, describe what you see and what you expected.
Add a screenshot
If you want to send the screen along, click Screenshot. For one part of the screen, click Mark area and drag a box around that part.
Send the message
Click Send. The window closes and the portal confirms that your feedback has been sent.
Your message includes the page you were on, your name, your email address, your organisation and technical details of your browser. If you send the feedback from the gateway page, support sees at once which gateway it concerns. The reply goes to the email address you sign in with.
Request a template
If a Modbus device is not in the template library, ModbusCloud creates the template free of charge as soon as the register details are available. Request it through the support page and send the brand, the type and the register map or the manual. What else is involved is described in Modbus device is not in the library.
Updated on 7 October 2026
Still stuck?
Email or call us. Include the serial number of the gateway, so we can take a look straight away.
Go to support