An OPC-UA Connection is used to communicate with an OPC-UA compliant server, such as the one the OPC-UA module provides.
The following steps walk-through connecting Ignition (as an OPC-UA client) to a OPC-UA server:
The Failover properties should be used when a single Ignition gateway needs to connect to a pair of redundant OPC-UA servers. The failover OPC-UA server will be used in the event the primary OPC server goes down. To enable failover, set the Failover Enabled property to true, and specify the Failover Endpoint. The Failover Threshold can be adjusted if desired.
The Backup properties should be used when a pair of redundant Ignition gateways are trying to look at the same OPC-server. Both the Backup Discovery URL and Backup Endpoint URL properties need to be configured.
You can access the OPC Quick Client from under the OPC Connections section of the Ignition Gateway Config section. It allows for quick, simple testing of any devices connected to the server.
You can browse by expanding tree nodes and read/write to tags by clicking on the [r] and [w] buttons next to those tags.
Subscriptions can be made by clicking on the [s] button. Clicking on the enable live values link will automatically refresh subscriptions and show live value changes (if there are any).
You can see the following OPC-UA Server Settings by going to the Configure section of the Gateway and then choosing OPC-UA > Settings.
|Authentication Profile||The User Source that the OPC-UA module will use to authenticate incoming connections against. By default, this is set to the opcua-module User Source. This profile is included in the default installation and has the following as its default settings:|
|Allowed Roles||Roles within the given User Source that are allowed to connect to the server. Multiple roles should be separated by a comma, for example, |
|Allow Anonymous Access||If checked, will allow anonymous connections to the server. Not checked by default.|
|Server Port||The port the OPC-UA module runs on.|
This is the local address that the Ignition UA server will bind to. It is also the address that will be used in a GetEndpointResponse, so it is important that this be an address reachable by any clients that wish to connect. Requires a module restart to take effect. This is useful if the server machine has a VPN connection or multiple adapters and is returning the wrong address.
|Minimum Sampling Interval||The fastest rate (in milliseconds) that the server will use to sample its underlying data sources. Requires a module restart to take effect. The default is 100.|
|Discovery Server Enabled||Select the check box if the local discovery server should be enabled. Requires a module restart to take effect. By default, the check box is selected or True.|
Expose Configured Tags
|Expose Tag Providers||If enabled, Ignition tag providers will be exposed through the OPC-UA server, allowing third party clients to access the tags configured in the system. By default, the check box is not selected or False.|
|Stale Threshold||The multiplier by which the server determines that updates from a driver have become stale. This period will be calculated as the fastest sampling rate for that node multiplied by this settings value. Default is |
|Allow Untrusted Certificates||Whether or not to automatically accept incoming certificates or to rely upon them being placed into the trusted certificate list before allowing a connection. By default, the check box is selected or True.|
|Discovery Server|| Address of the discovery server to register with. Default is |
|Discovery Registration Frequency||Frequency (in minutes) at which the server will attempt to register with the discovery server. Default is |
|Auto-cast Writes|| Attempt to auto-cast incoming writes to the correct DataType before rejecting them with a |
Getting data from your PLC into Ignition is a two step process:
It requires you to touch both the Ignition Gateway and the Ignition Designer. There are also some limitations as to what kind of devices you can connect to Ignition and these are explained throughout the user manual, however included below is an overview of what you can expect when it comes to compatibility.
Most commonly you will be adding a device that is supported by one of the built-in device drivers. The first step is connecting your device to Ignition. This is done through the Ignition Gateway Configuration section under the OPC-UA -> Devices page.
As long as all the device information you entered was correct you should see your device in a "Connected" state. The only exception to this is if you chose to add a Siemens or Modbus device. Since these devices don't support the browsing of tags you will have to create and address some tags in the Ignition designer before the device will stop cycling from a connected to disconnected state.
If you need to address your tags for your Siemens or Modbus device you'll want to read about adding Tags in the Ignition Designer as well as how addressing works for the different protocols. You will have to first add a tag in the Ignition designer and then edit the OPC Item Path of the tag using the appropriate addressing scheme.
If your device does not have an Ignition driver, you can use a 3rd party OPC server to connect to your device and then have Ignition connect to the server as a client. If the OPC server talks OPC-UA, you can add a new OPC-UA server connection in the Ignition Gateway. Configuration will be different depending on what OPC server you are using but the following is an example of a popular solution, connecting to KEPServer via OPC-UA, see Connecting to Kepware OPC-UA.
The following section provides a detailed walk-through on how to connect to an OPC server using the OPC-COM module. If Ignition doesn't have a driver for your device and you don't have an OPC server that talks OPC-UA, you have to connect using the OPC-COM module, see Connecting to OPC Classic (COM).
Tags are how Ignition represents your PLC tags. You create Tags in the Ignition Designer and then you can use these tags to store history or display PLC data in your projects.
For the most part, Allen Bradley devices support browsing of tags in the PLC. There are a few exceptions like the MicroLogix 1200/1500 for which you have to manually address your tags. For now we will focus on creating tags from devices that support browsing.