Message when adding or saving a Modbus device

The portal shows most messages at the bottom right of the screen. They appear after Add in the Configure Modbus device window, after Save under Connection on the page of a Modbus device, or after you delete it. After an error message at Add, nothing has been added. First compare the address on the Modbus device itself with the address in the portal.

The address is already in use on this gateway

The portal rejects the address because another Modbus device on this gateway already has it. The table shows which message you get where, with address 3 as an example.

A slave address or unit ID occurs once per gateway, also across a Modbus RTU device and a Modbus TCP device. The address of a Modbus device is shown on its page under the name. More about addresses is in Set the address and connection of a Modbus device.

If the message appears on the page of a Modbus device, the portal may already have moved the registers to the new address. Do not change the address again. Contact support instead.

The Modbus device is already there

Under Modbus devices on the gateway page, check whether the Modbus device is already in the list, for example after automatic search. If it is, you do not need to add it again.

Another Modbus device has the same address

The gateway cannot tell two Modbus devices with the same address apart. Set a free address on one of the two yourself and enter that address in the portal.

Two Modbus TCP devices have the same unit ID

The gateway tells Modbus devices apart by unit ID, not by IP address. A different IP address or port therefore does not help. Set a different unit ID on one of the two Modbus TCP devices yourself, then add it again.

The address is out of range

The portal reports Slave ID must be between 1 and 247 for Modbus RTU or Unit ID must be between 1 and 255 for Modbus TCP. The address field is then empty, 0 or too high. In the Configure Modbus device window, the browser already blocks a number outside the range at the field.

On the page of a Modbus device, the message also appears when you change the Protocol to Modbus RTU with a unit ID above 247. Enter the address that is shown on the Modbus device itself. If that is 0 or higher than allowed, set an address within the range on the Modbus device.

The bus settings differ from the RS485 bus

The portal reports, for example, This Modbus device talks at 19200 8E1. The other Modbus devices on this gateway talk at 9600 8N1. Set it to 9600 8N1 and search again. The notation 9600 8N1 stands for 9600 baud, 8 data bits, no parity and 1 stop bit.

This message appears only after automatic search. In the Automatic search window it appears in the block of the Modbus device. If you choose a template yourself through Other Modbus device, it appears at the bottom right after Add.

The bus settings apply to the whole gateway. If other Modbus RTU devices are already on the bus, the portal leaves those settings as they are. Set the Modbus device itself to the bus settings of the gateway from the message. Then search again as described in Automatic search and add the Modbus device.

If you prefer to move all Modbus RTU devices to the new settings, change the bus under Modbus RTU-bus (Modbus RTU bus) in Gateway settings. Other messages during the search are covered in Automatic search does not find everything.

The configuration could not be sent to the gateway

The portal has saved the change but could not send the new configuration to the gateway. The table shows which message you get after which action.

If the gateway is offline, this message does not appear. The gateway receives the latest configuration as soon as it is connected again.

Every configuration contains all Modbus devices and registers of the gateway as they are in the portal. The portal sends a new one when you add or delete a Modbus device, add, change or delete a register, or save a connection. The missed change then goes along. Save under Connection stays grey after the message until you change something.

If the deleted Modbus device was the last one on the gateway, no configuration goes out until you add a Modbus device. Until then the gateway may read the old address, without the readings reaching the portal. If no values arrive after the next configuration, follow Modbus device shows no values.

The gateway keeps reading a deleted address

If you delete the last Modbus device of a gateway with older software, the confirmation says This gateway still runs older software and keeps reading the address until it is updated. Those readings are not stored.

Older software on the gateway ignores a configuration without Modbus devices. The gateway then keeps reading the old address, but the portal does not store those readings. If you still want to delete the Modbus device, click Confirm. What is lost is described in Delete the Modbus device.

Add, save or delete fails without explanation

The portal reports Add failed, Save failed, Delete failed or a technical message. Add failed can also appear after Copy and use in the library. Refresh the page, check what has been saved and try again.

Contact support

If it still does not work, contact support via the support page. Send the serial number of the gateway, the text of the message and the protocol and address of the Modbus device.