Transport Protocols for the Generic Input Data Link
The Generic Input Data Link is capable of receiving data from an outside source either through a TCP socket connection or through UDP packets. These different methods of data delivery are referred to as transport protocols. The use of UDP packets allows for faster data transmission by eschewing the use of error correction or retransmission. However, UDP packets can get lost if used on a busy network. If a TCP socket connection is used there is additional network traffic overhead, but packets cannot get lost in the network.
If a TCP socket connection is used, it can be initiated by the external source or it can be initiated by the Generic Input Data Link. These two ways of initiating the TCP socket are referred to as TCP Server or TCP Client mode in the Generic Input Data Link Properties dialog box. In TCP Server mode, the data link listens to the port for a connection to be initiated by a third-party client data source. The listening approach allows multiple third-party clients to transfer data through a single connection. UDP also employs a listening approach. In TCP client mode, the data link itself initiates and maintains a connection to a single host and port number where a server resides that will send messages.
Transport Protocol | Third-Party Data Sources per Connection | Connection Properties | Pro | Con |
|---|---|---|---|---|
TCP Server | Unlimited |
| Data transmission guaranteed | More network overhead |
TCP Client | One |
| Data transmission guaranteed | More network overhead |
UDP | Unlimited |
| Less network overhead | Data transmission not guaranteed |
The Generic Input Data Link allows you to set up multiple connections for external data sources. These connections can use different transport protocols and use different text formats for the data being transmitted. Connections are configured and managed in the Generic Input Data Link Properties dialog box. New connections can be created, and existing connections can be modified or deleted.
Because TCP Server connections listen on a port, the port number specified for each connection must be unique among existing TCP Server connections. In a similar way, the port number used by each UDP connection must be unique among UDP connections. For TCP Client connections, the combination of port number and host to connect to must be unique.