difference between em client free and pro

I hope this helped you to understand the difference. In future if you want to migrate to any operating system then it will not be a ahead ache. The only difference is the JavaScript code that we give them. All the Expo apps do share the exact same native runtime (React Native + ExpoKit). OPC UA servers can be OS independent (it purely depends on type of SDK). The Expo client is a generic client that permits to load any app that is compatible with Expo. Because, there are some products in which with the Old OPC DA products data can still be collected with the new OPC UA based products. My suggestion is, go with OPC UA irrespective of whether you have OPC DA servers or not.

it depends on SDK to support either both or any one of them. Where is OPC UA is about TCP/IP and/or HTTPS. Some using some of the OPC UA SDKs the Servers can be created on a platform where OS is not present Where is OPC UA is independent of Operating system. Which is the conversion formula used, whether the variable is accessible by user or not! to name few). Where as OPC UA has data and information Modelling, Along with VQT, there are many attributes/Properties which can be shared between server and client about a variable (in simple example, Say describing what this variable doing. Only information which was transferred between server and client is VQT (Value Quality and Time). Where there was data modelling (not to a greater extent like OPC UA has).

OPC DA, is older version of OPC specification. Specification doesn't says anything about platform, OS etc.

OPC UA is the Unified Architecture of OPC.

Difference between em client free and pro