Automatic search does not find everything

After the search, the Automatic search window shows each Modbus device it found in its own block, or No Modbus devices found. If you searched with counts entered, search again first with I don't know yet, just search everything. How the search works is explained in Find Modbus devices with automatic search.

The search only reads. You therefore correct an address or bus setting on the Modbus device yourself.

Automatic search is missing

The Add Modbus device window then shows only Library and Custom template. In the demo account the tile is never there.

The gateway does not report that it can search

Only a gateway that reports it can search gets the tile. Older gateway software does not report this. Add the Modbus device as described in Choose a template from the library.

Your role may not add Modbus devices

Searching works with the role Owner, Admin or Technician. With the role Read only, the Add Modbus device button is missing too. An owner or admin changes your role, as described in Team members and roles.

The search finds nothing on the RS485 bus

The window reports No Modbus devices found. Or there are blocks, but a Modbus device on RS485 is missing. Fix the cause below and search again.

The Modbus device uses different bus settings

The table shows which bus settings the gateway tries. It always searches with 8 data bits.

With counts entered under What did you connect?, the gateway stops at the first setting on which a Modbus device answers. Searching everything tries all of them.

If the Modbus device uses anything else, set it to the bus settings of the gateway, by default 9600 8N1. These are described in Gateway settings.

The address is outside the common addresses

With counts entered, the gateway tries addresses 1 to 10, 100, 126, 200 and 247. Searching everything then tries every address from 1 to 247, but only on bus settings on which a Modbus device already answered. If no other Modbus device answers on a common address with those bus settings, searching everything does not find it either. Give it a free address from 1 to 10 and search again.

The wiring is wrong

If plus and minus are swapped, the Modbus device does not answer. Check the bus with Connect the RS485 bus.

The address and settings are unknown

Find the address and bus settings on site with ModbusCloud Diagnostics, as described in Connect and find a Modbus device with Diagnostics. Disconnect the bus from the gateway first, because two masters on one bus produce garbled answers.

A Modbus TCP device is missing

There is no block with the IP address of the Modbus TCP device. Add it through Library with IP address and port, as described in Set the address and connection of a Modbus device.

The Modbus device uses a different port

The gateway only searches on port 502.

The Modbus device is on a different network

The gateway searches the network on its LAN port. If its internet runs over the cable on the WAN port, it also searches that network when it uses private addresses. Over 4G it searches only on the LAN port.

Per network, the gateway never searches beyond the /24 around its own address. If it is on 192.168.10.5 in a 192.168.0.0/16 network, it does not find a Modbus device on 192.168.20.30.

The unit ID is outside the common unit IDs

With counts entered, the gateway tries unit IDs 0 to 3, 100, 126 and 255. Searching everything tries every unit ID from 0 to 247 and 255. The search never finds a unit ID from 248 to 254. Add such a Modbus device through Library.

A found Modbus device is not recognised

During the search, such a Modbus device is called, for example, Modbus device at address 3 or Modbus device at 192.168.10.20. Afterwards the block shows only the option Choose brand and model yourself.

The gateway does not know the type

Click Choose brand and model yourself and choose the template as described in Choose a template from the library. The address and connection from the search are already filled in.

If the type is not there either, follow Modbus device is not in the library.

The gateway chooses the wrong type

The options are numbered, the most likely first. If the values under the chosen option are wrong, choose another option. If the right type is not listed, click Other Modbus device.

Adding gives a message at the block

The Modbus device has then not been added.

The other Modbus devices use different bus settings

The message starts, for example, with This Modbus device talks at 19200 8E1. It then gives the settings of the other Modbus devices on the gateway. All Modbus RTU devices on a gateway share the same bus settings. Set the Modbus device to the settings from the message and search again.

The address is already in use

The block reports, for example, Address 3 is already used by another Modbus device on this gateway. Each address or unit ID occurs once per gateway, also for Modbus TCP on different IP addresses.

Set a free address on the Modbus device and search again. If you have already added it, skip the block with Not on this bus.

The Modbus device only answers on unit ID 0

The message starts with This Modbus device only answers on unit ID 0. Set a unit ID from 1 to 255 on the Modbus device and search again.

The search stops or only partly succeeds

The window then shows a message.

The gateway is offline

Under What did you connect? it says Gateway is offline and the buttons to search do not work. Fix that first with Gateway is offline.

The gateway does not pick up the search

After 45 seconds the window reports The gateway has not picked up the search yet. Click the cross next to the title (Cancel search) and confirm with Stop searching. Try again later.

The search did not finish

The window reports The search did not finish. Try again. Click Try again, or Back if that button is not there.

The gateway cannot search automatically yet

The window reports This gateway cannot search automatically yet. Trying again does not help. Add the Modbus device through Library.

Part of the search failed

Above the blocks there is then one of these messages.

• The bus search failed.
• The network search failed.
• Part of the search failed.

If part of the search got stuck on an error or on the time limit, the window shows what the gateway did find. Add those Modbus devices and search again.

Contact support

If it still does not work, contact us through the support page. Send the serial number of the gateway, the brand and type of the Modbus device, the address or IP address and the message from the window.