MTConnect

An MTConnect agent is software that acts as a bridge between manufacturing equipment to generate data and the software applications that consume data. The raw data from the equipment is normalized by the agent and converted into a structured format before it is served to other specialized applications that monitor and analyze the information.

MTConnect and OPC UA are communication standards commonly used in manufacturing. OPC UA is a specification framework that can be used to build many different protocols, whereas MTConnect is itself a protocol. For this reason, comparing the two becomes tricky, so for this discussion we will compare the OPC UA data access protocol with the MTConnect protocol.

While OPC UA has a more general reach, MTConnect is often found in, but not limited to, environments where CNC machines are part of the manufacturing process. Both protocols were designed to support human-readable XML payloads. However, OPC UA is more commonly used in its binary format. One key difference is that MTConnect is a read-only protocol, whereas OPC UA allows for reading and writing of data points found on the manufacturing equipment.

In an MTConnect implementation, there are three software components: adapter (as required), agent, and client.

The optional MTConnect adapter converts low-level data into a plain-text, pipe-delimited string format expected by the agent. The agent consumes the string, parsing at delimiters, and places the parsed values into a previously configured XML structure.

When a machine implements MTConnect, the machine vendor or a third party provides the MTConnect agent, and if necessary, an MTConnect adapter to convert low-level signals into high-level string representations to be consumed by the agent. The MTConnect client then interrogates the agent using HTTP to retrieve machine data like status codes and set point. The machine data is rendered in an XML structure by the MTConnect agent. The MTConnect client consumes the XML structure, making use of the included information as needed.

In Kepware, each unique element of the provided XML structure is parsed into an atomic tag, like integers, floating points, strings, and Booleans, and the data distributed to the clients and plug-ins requesting it.

Multiple channels connecting to a single agent is possible and depends on the agent’s capabilities. Using multiple channels to connect to a single agent and spreading your complete tag load across the two connections may increase aggregate read performance.

When tuning for optimal performance, users should consider three properties located in Device Properties > Settings:

• “Close Agent Connection After Each Request;” default is enabled and closing/reopening after each request may arbitrarily decrease performance.
• “Read All Items in a Single Request;” default is set to enable, but if only a small subset of data from the agent is desired, users might experience better performance by setting to disable and adjusting the Items Per Request option to match the desired tag count.
• “Schema Tag Validation;” default is enabled, and for certain reasons, including initial integration and testing, it can be useful to disable. This will stop the driver from invalidating MTConnect agent responses that have data items included that do not match the preinstalled set of MTConnect XML schema files available to the driver. Validation can be optionally reenabled after matching schemas are provided to the driver. See the driver Help file for location of the driver’s schema file directory.