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If Diagnostics does not identify a Modbus device with certainty, you import the registers from the manual. How identification works is described in Identify a Modbus device, read and write values. A device type in Diagnostics is what the portal calls a template. The manual stays on your computer.
What you need
- ModbusCloud Diagnostics on a computer with Windows or macOS. How to install it is described in Install ModbusCloud Diagnostics.
- The manual with the register table of the Modbus device.
- For the check, the Modbus device, connected and added in Diagnostics. How to do that is described in Connect and find a Modbus device with Diagnostics.
- To transfer the device type to the portal, the role Owner, Admin or Technician.
Open the manual
After these steps, the registers from the manual are listed in the Read a manual window. While you add a Modbus device, the button I have the manual appears if identification found no device type that fits with certainty. If you click it, the program first adds the Modbus device without a device type. On the Live tab, the button is there as long as the Modbus device has no device type and identification found nothing or only a type marked Possible.
Open the window
Click I have the manual at the Modbus device. Without a Modbus device, click the document icon (Read a manual) to the right of the heading in Library.
Open the file picker
Click Choose file. Or drag the file to the box Drop the manual here.
Choose the manual
Choose the manual. The program shows the registers it found per table, with the page number for a PDF.
The program reads a PDF with text, an Excel file (.xlsx), CSV, TSV and a text file. A scanned page has no text. The program skips it and gives the page number. It does not open an .xls file, so save that in Excel as .xlsx or CSV.
If the program finds no table, it reports No register list found in this manual. Paste the table as text instead.
Copy the table
Copy only the register table from the PDF or from Excel.
Open the text box
Click Paste a register list.
Paste the table
Paste the table into the text box.
Have the text read
Click Read. The program shows the registers it found.
Choose registers
After these steps, the device type has a brand, a name and the registers you want to read. Above the list are the baud rate, the parity and the slave address that the manual states. The program fills in 9600 baud, 8N1 and address 1 for whatever the manual does not state.
The program converts addresses such as 30001 or 40001 to the address counted from 0. The list then shows both, for example 30001 → 0.
Enter the brand
In Brand, enter the manufacturer. If the program already found the brand, check it.
Enter the name
In Name, enter the name of the device type. For a file, the file name is already there.
Select the registers
Select the registers you want to read. Measured values with a common unit, such as V, A, W, kWh, Hz and °C, are already selected.
Of each table, the selected registers are in view. The others appear after you click the line with the number of other registers. You find a register by name or address in the field Find a register….
Check the list on the Modbus device
After the check, you know which registers are right on the Modbus device. If the manual differs in address, function code, word order or scale, the program adjusts the list. The program only reads and writes nothing to the Modbus device. The check is not mandatory.
If the gateway is on the same RS485 bus as your USB-RS485 adapter, disconnect its A and B wires while you check. Two masters on one bus give garbled answers.
Choose the Modbus device
If you opened the window from Library, choose the Modbus device in Choose the device…. From a Modbus device, the choice is already fixed.
Start the check
Click Check on the device. The program reads the registers twice, with 3 seconds in between.
Compare the values
Compare the values in the list with the display of the Modbus device. Each checked register shows its value with a tick.
Choose a reading
If the program asks Which values are right?, click This one is right at the values that match the display or your own measurement. If you do not know, click I don't know. The list then stays as the manual gave it.
The table shows what the messages under the button mean.
| Message | Meaning | What you do |
|---|---|---|
| Addresses or scale were adjusted to what the device shows. | The manual differed and the program adjusted the list | Nothing |
| A number of registers are not in the Modbus device and have been unselected | The Modbus device refuses those registers | Nothing, they do not go into the device type |
| The device only shows zeros right now. Check again when it is running. | With only zeros, the program cannot compare anything | Click Check again when the Modbus device is running |
| The device does not answer. Check the connection and try again. | No answer comes back | Find the cause with Find faults with the Diagnostics tab and the console |
Save the device type
Click Save as device type. The button works as soon as at least one register is selected and no check is running. If you opened the window from a Modbus device, the program uses the device type for it straight away. The Live tab then shows the values with name and unit.
The device type is then in Library with the label Mine. It contains only the selected registers and the connection details from above the list. From now on, identification also compares a Modbus device with this device type. If all selected registers were checked, it says Verified on hardware, otherwise Unverified.
The program stores the text of the manual with the device type. You search it later with Search the manual at the device type in Library, for example for the baud rate.
Transfer the device type to the portal
Diagnostics turns the device type into a JSON file that the portal reads in as a template. ModbusCloud also creates a missing template free of charge. How to request one is described in Modbus device is not in the library.
Open the library
Click Library in the sidebar of Diagnostics.
Open the device type
Click your device type in the list. With the choice Mine, only your own device types are in the list.
Open the export
Click Export as.
Choose the format
Choose ModbusCloud gateway JSON.
Save the file
Save the file. Diagnostics reports where it is.
Import it in the portal
Import the file in the portal with Import on the page of a template, as described in Create a custom template.
After Import and before Save, check the Protocol of the template. If the manual does not clearly state RTU or TCP, there is no valid choice there. Then choose Modbus RTU or Modbus TCP.
Look at the column Data type as well. The gateway only reads int16, uint16, int32, uint32 and float32. Remove a register with another data type, such as text or a 64-bit number, with the bin (Delete).
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.
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