MQTT

Message Queue Telemetry Transport (MQTT) is an OASIS standard messaging protocol for the Internet of Things (IoT). It is designed as an extremely lightweight publish or subscribe messaging transport that is ideal for connecting remote devices with a small code footprint and limited network bandwidth. It must run over a transport protocol that provides ordered, lossless, bi-directional connections - typically, TCP/IP, but also possibly over QUIC It is an open OASIS standard and an ISO recommendation (ISO/IEC 20922). For more information, see MQTT: The Standard for IoT Messaging.

The maximum number of tags depends on the FactoryTalk Linx Gateway activation. The total number of publisher and subscriber tags can't exceeds the FactoryTalk Linx Gateway activation.
The data format is JSON text with options to format similar to FactoryTalk Optix, Plex APM's flat format, or rich format similar to FactoryTalk Edge Gateway.
The connection to the broker can optionally support SSL/TLS security.