What Is MTConnect?

MTConnect is an open, royalty-free manufacturing standard for getting data out of CNC machine tools and other shop-floor equipment in a consistent form. It defines both a protocol, based on HTTP and XML (JSON is also supported in current versions), and a common vocabulary: a spindle speed, an execution state or an emergency stop means the same thing whichever company built the machine.

The standard grew out of a 2006 call by the Association for Manufacturing Technology (AMT) for an open way to connect machine tools to the internet. It was developed with the University of California, Berkeley and Georgia Tech, version 1.0 was released in December 2008, and it is maintained by the MTConnect Institute. It is also published as an American National Standard, ANSI/MTC1.4-2018, and has continued through the 2.x series since.

MTConnect is deliberately read-only. It describes how software reads data from a machine, not how it writes to one, which keeps it out of the control path and makes it a natural fit for machine monitoring and analysis.

An MTConnect system has three roles. They can run on the machine’s own controller, on a small computer beside it, or on a server elsewhere on the network.

Each agent describes its devices as a tree of components: a controller with one or more paths, linear and rotary axes, spindles, coolant, door and other systems. Every value in that tree is a data item in one of three categories.

Samples are continuously changing numbers, such as spindle speed, load, feed rate and axis position. Events are discrete states and values, such as execution state, controller mode, program name, part count and tool number. Conditions report health as normal, warning or fault, with the alarm text. Because the names and measurement conventions are standardised, a monitoring system can show utilisation and alarms for different brands of machine without custom mapping for each one.

MTConnect and OPC UA are often compared, and many newer machines support both. In 2019 the MTConnect Institute and the OPC Foundation published a joint companion specification that maps the MTConnect model into OPC UA.

In practice the choice is often made by the machines on site. Where both are available, MTConnect is quick to set up for monitoring, while OPC UA suits plants that also need to write data back or standardise on one protocol across all equipment. Our white paper on OPC UA vs MQTT covers how the data then travels on to the cloud.

CNC machine tools often run for 25 years or more, so most shops have a mix of machines with native MTConnect, machines with another Ethernet interface and machines with only an RS-232 port, often used for DNC program transfer. An adapter running on an edge computer can cover all three: it reads the controller over Ethernet, reads status over serial, or reads the stack light through digital inputs, and feeds a single agent.

Our industrial IoT gateways and DIN rail PCs run Linux or Windows, so the open-source MTConnect agent and adapters can be installed on them. Most of our gateways list RS-232/422/485 ports, and where a computer needs more, our serial I/O modules add ports for a row of older machines.

We supply gateways and DIN rail PCs for MTConnect projects with the operating system, serial and network interfaces configured as standard, ready for the agent and adapters your machines need.