Category: Knowledge Base

Each Tag has a Target Parameter that can be enabled to write a value back to an OPC Item. Because each Tag can have another Tag as a data source a Tag value can be transferred to unlimited numbers of OPC Items on both a local OAS Service or on other remote OAS Services.

Set as target in Configure tags.

Here you will find miscellaneous resources that can help you use Open Automation Software more efficiently.

Networking in OAS is a core feature and allows you to design your network architecture in the way that best suits your business needs and your desired level of security.

OAS uses TCP communications with encryption and compression to achieve the performance, reliability and security that you need. When data is transported to clients, only the data each client has requested is transferred. Network traffic is minimized by ensuring that the packet size is as small as possible. This is achieved using a compressed binary payload to transfer the value, timestamp, and quality of each tag value to the client. To further optimize the data transfer, once all of the requested values are transferred, only tag value changes are transmitted in the next packet.

Whether you want to run OAS as a single server instance, separate your OT and IT networks, isolate a critical network with one-way communications, or host OAS in a DMZ or internet facing network, the OAS networking features have you covered. There are three key networking methods included with a network enabled license that you can use independently or together to achieve almost any networking topology that you require.

Basic Networking

The Basic Networking method is the most common method and is used whenever your OAS instances have a static IP address, fixed host name or a registered domain name and the instances are reachable on the network. This is a direct and bidirectional method of communication used for OAS Engine to OAS Engine and OAS Engine to client data transfer and configuration.

👉 More information about Basic Networking 🔗

Live Data Cloud

The Live Data Cloud method is useful for allowing clients or OAS Engines on an external network (for example a Public Zone) to communicate with OAS Engines that are within an internal network (for example a Private Zone) and may not always have a fixed IP address. This method is also commonly used to provide external and public clients access to data without exposing internal OAS Engines through the use of a DMZ networking zone.

The Live Data Cloud method works by having an OAS Engine with Live Data Cloud enabled hosted in a network between the private network and the public network, like in a DMZ as mentioned previously, and registering this instance with a registered domain or fixed IP address (for example: iotdata.xyz). The internal OAS Engines will register themselves using an alias in the Live Data Cloud instance. The Live Data Cloud instance will handle the data routing between clients and external OAS Engines and the internal OAS Engines without exposing the internal engines to the public network.

👉 More information about Live Data Cloud 🔗

Unidirectional Network Gateway

The Unidirectional Network Gateway method of communication is used where a networking architecture requires the most secure isolation of networks possible. This method can be used where all standard bidirectional TCP traffic to and from any other network is blocked. This special configuration uses the UDP protocol to ensure that data changes can only flow out of the secure network and never in. The UDP protocol is specifically designed for this type of data broadcasting where no replies from the receiving network are expected.

👉 More information about Unidirectional Network Gateway 🔗

Technical Information

Basic Networking and Live Data Cloud

OAS Engines and clients will poll the OAS Engine for new data every 30ms by default. This can be adjusted in the OAS Configuration tool using Configure > Options > Networking tab. This value should be increased to 100ms if there are more than 100 client connections, and to 1000ms if there are more than 1000 client connections.

On the first poll, all requested tag values are transmitted to the requesting OAS Engine or client.

After the first poll, only data changes are transmitted to the requesting OAS Engine or client.

If a client does not receive a response from the OAS Engine being polled the connection will be considered lost immediately on both the server and the client side.

If you have several remote clients that need the same data from a remote service, a second service can be set up with remote Tags as a data source from the remote service, and all of the clients can communicate with the second service. This would be for all read-only data to reduce the communications from a data source service from a remote location with low bandwidth. Any points that need to be written can be made directly by each client to the remote service.

Unidirectional Network Gateway

All tag values configured in the UDP Broadcast are transmitted to the UDP Receiver instance in each data transfer.

The transmitting node will not know that the receiving node has received the values; thus, store and forward are not supported by this networking method. The receiving node does have an adjustable timeout, so if values for each tag are not received within that specified time, the quality of the local tag will be set to bad quality, indicating a network loss.

Communication Methods by Feature

All features of Open Automation Software including configuration tools and all .NET components support remote connections over your LAN, WAN, VPN, and the Internet. Visit the OAS IoT Network 🔗 page for comparison of advantages over typical cloud networks which are push/pull communications.

Visit the Getting Started-Networking 🔗 page for helpful features like network node aliasing in client applications and how to check if your TCP port is open.