PLC Instances

A PLC Instance is a connection between the MVS Server and a block of memory addresses on a specific PLC.

MVS Communicates to a PLC through a OPC Server (usually kepware). The actual connection to a PLC is defined by the OPC server, while MVS only requires configuration to talk to the OPC Server.

Adding A PLC Instance

Before adding a PLC Instance the following is required:

  • Kepware is installed and configured for OPC UA communication.
  • The API in kepware should be properly configured to allow MVS to automatically generate tags.
  • A plc Connection is configured to communicate to the kepware instance.
  • A Channel & Device is configured in kepware to communicate with a specific PLC.

If all of the above is properly configured, create a new PLC Instance in MVS by navigating to the appropriate PLC Connection and click Add New. Filso the t Instance.

mvs channel/device

Once the instance is saved a dialog will appear that will allow a user to auto-generate the tags in the Kepware instance. Fill in the fields to customize the tag addressing for the specified device and verify the addressing is correct in the sample section. To create the tags in kepware click on the Create button.

mvs channel/device

Monitor PLC Instance

To monitor the status of a PLC Instance, navigate to the Status page and click on the info icon of the PLC Instance.

Diagnose Connection

The PLC Info pane will display any details about the connection to the plc. If it displays Disconnected the Status should give some indication as to why.

In the following image the Kepware OPC server has lost the connection to the PLC, which might indicate a networking issue:

In this example the PLC has not properly defined its memory addresses. The kepware Tag for the Heartbeat and InspectionPointId can't be found at the expected memory address. This can be fixed by updating the address on the PLC (recommended), but also by editing the address manually in kepware. Memory addresses are described in the docs on plc configuration.

In the next example MVS can't reach the OPC Server defined by the PLC Connection. This usually means that either the PLC Connection is not properly configured, kepware is not running, or its OPC UA connection is not accepting the MVS Server connection.

Monitor Values

This page will show realtime information about the tags connected to the PLC instance.