Configure endpoints

An endpoint is the Modbus TCP connection that parameters read and write through. Field rules, defaults, and the status vocabulary are in the endpoints reference.

To change endpoints, you need the editor, admin, or owner role. Endpoints are in Setup… → Endpoints. Inside Setup, the sidebar lists every section.

Create a TCP endpoint

Use a TCP endpoint for a device or gateway with a host name or IP address that the Overvis server can reach. For a device on the Overvis VPN, create a PIN or WireGuard endpoint instead.

1. Find the device’s host name or IP address and its Modbus TCP port. The usual port is 502; many devices allow another one. Use a stable DNS name or a static IP address. Private, loopback, and Overvis VPN addresses are refused (TCP endpoints).
2. In Setup → Endpoints, select Create endpoint.
3. Under Kind, choose TCP. The dialog starts on PIN.
4. Enter a name, the host name, and the port, then save.
5. Make sure the endpoint is Enabled.
6. Open the endpoint’s status page and wait for Connected.
7. Add parameters that use this endpoint.

Keep the default TCP settings unless the site is known to be slow. To change them, see Change the host, port, or TCP settings.

Create a PIN endpoint

Use a PIN endpoint for a supported Overvis device. The device must be registered and online on the Overvis VPN.

1. In Setup → Endpoints, select Create endpoint. The dialog starts on PIN.

2. Enter a name and the device’s 8-character PIN.

3. For an MC252, confirm that the device is yours within two minutes:

   • press the R button on the device, and the dialog continues on its own; or
   • if the device screen shows an 8-digit code, enter that code.

   If the dialog reports that the firmware is too old, update the MC252 to firmware 49 or newer in its web interface (Administration), then start again. After five wrong codes, start again. Other PIN products skip this step.

4. Save. Make sure the endpoint is Enabled.

5. Open the endpoint’s status page and wait for Connected. Active address shows the VPN address.

6. Add parameters that use this endpoint.

Some devices must first allow Modbus access over the Overvis VPN in their own settings. The device manual describes it.

If a device pairing code was shared by mistake, contact Overvis support.

To create an MC252 PIN endpoint through the API, see MC252 presence confirmation.

Create a WireGuard endpoint

Use a WireGuard endpoint for a third-party device that runs a WireGuard client, for example a Teltonika TRB256 used as a Modbus TCP gateway.

1. On the device, generate a new WireGuard key pair. Do not reuse a key from another VPN or from a device connected by PIN (WireGuard endpoints).
2. In Setup → Endpoints, select Create endpoint, and under Kind, choose WireGuard.
3. Enter a name, paste the device’s public key, and set the device’s Modbus TCP port. Save.
4. In the Documentation dialog that opens, copy the configuration to the device. Replace the PrivateKey placeholder with the device’s private key that matches the public key. If the dialog says the address is not assigned yet, wait: it fills in the configuration by itself.
5. Apply the configuration on the device and confirm that the tunnel is up.
6. Make sure the endpoint is Enabled. Open the status page and wait for Connected. Active address shows the reserved VPN address.
7. Add parameters that use this endpoint.

To open the configuration again, select the Documentation icon on the endpoint’s row. To use a new key pair, delete the endpoint and create it again with the new public key. Keep using the same key pair for as long as the endpoint exists.

Change the host, port, or TCP settings

1. In Setup → Endpoints, open the endpoint’s Edit dialog.
2. Change the host name or port (TCP), the port (WireGuard), or the settings in the TCP section. To pick a TCP setting, use the table below.
3. Save, then compare Setup address with Active address on the status page.

Symptom	Setting to change
Connection never completes on slow WAN	Increase Connect timeout
Rapid reconnect storms	Increase Connect retry delay
Occasional late responses	Increase Response await timeout or Total request timeout
Too much chatter or keepalive problems	Adjust TCP keepalive interval (0 turns it off)
Framing errors on a bad link	Change Disconnect after protocol errors (empty never disconnects)
Overload on small devices	Lower Max simultaneous requests

Leave the other settings at their defaults. Most sites never change them. Each setting is described in TCP settings.

Enable or disable an endpoint

1. In Setup → Endpoints, turn the endpoint’s Enabled switch on or off.

A disabled endpoint is not used until you enable it again. A WireGuard endpoint keeps its key and address while it is disabled.

Delete an endpoint

1. Move or change the parameters, edge programs, automations, and alarm rules that use the endpoint, or delete them.
2. For an MC252 with edge programs, remove the programs from the device first. See Remove programs from a device.
3. In Setup → Endpoints, select Delete endpoint on the row and confirm.

Deleting a PIN endpoint does not disconnect the device from other workspaces. Deleting a WireGuard endpoint releases its public key and VPN address.

Disconnect an MC252 from other workspaces

1. Open the MC252’s status page. The status line shows Also connected in with the other workspaces.
2. Select Disconnect….
3. Press the R button on the device, or enter the 8-digit code if the device screen shows one.

Parameters in the other workspaces that used the connection stop working.

Open the device web interface

1. Open the status page of a PIN or WireGuard endpoint and select the Device UI tab. You need the editor, admin, or owner role.
2. Wait for the progress bar. The first opening over a slow connection can take a minute or more.
3. To use the interface in its own window, select Open in new window.

Find devices on an MC252 RS-485 bus

You need an enabled MC252 PIN endpoint, a reachable MC252, and a FAT or FAT32 microSD card in it for identification. How device find works is described in RS-485 device find.

1. Ask the assistant to find the devices behind the MC252. A progress card shows the tries, the unit IDs found, and Cancel.
2. Wait while the assistant identifies the model of each unit ID. A second progress card shows the identification.
3. For each model with a parameter template, select Allow to add its parameters. For an unknown device or a model without a template, answer the assistant’s question.
4. If the scan finds nothing, check the wiring and the A and B lines, and tell the assistant the baud rate if you know it.
5. If the assistant reports an SD card sync failure, insert a working FAT or FAT32 card and check the MC252’s power supply. Then ask the assistant to identify the devices again. The unit IDs it found are kept.

Fix connection problems

1. Check that the endpoint is Enabled.
2. Compare Setup address with Active address on the status page:
   • TCP: check the host name and port.
   • PIN: check the PIN, and that the device is still online on the VPN.
   • WireGuard: check that the configuration is applied, and that the device is still online on the VPN.
3. If the state is Error, Disconnected, or Connecting, read Last error: it keeps the most recent failure until a connection succeeds.
4. If the state stays Connecting, check the network path, the device’s power, and the IP address (TCP), or the device’s VPN connection (PIN, WireGuard).
5. Check that the Overvis server can reach the device through any firewall, and check the device’s Modbus settings.
6. If the endpoint is Connected but parameters fail, check each parameter’s unit ID, table, and addresses, and the device’s register map. Check that the parameter’s endpoint still exists and is enabled before you change register maps.
7. If you cannot change the endpoint, ask an admin for the editor role.

Parameter errors that point at the endpoint are listed in endpoints and parameters. If you see Connector rejected, retry, then check the setup. For device wiring and register questions, ask the assistant for the device’s manual.