Open Protocol for Tightening Tools: Complete Guide

Open Protocol for Tightening Tools: The Industry Standard for Connected Fastening

Modern assembly lines depend on much more than achieving the correct torque.

Industrial fastening tools increasingly need to communicate with Operator Guidance Systems, process control software and other production equipment. The production system may need to select the correct tightening program, enable a tool at the right assembly step, monitor torque and angle, receive the tightening result and prevent the operator from continuing when an operation fails.

This applies across a wide range of assembly tools, including an electric nutrunners, electric screwdrivers, digital torque wrenches, rivet tools, pulse tools and other intelligent electric torque tools.

The challenge is communication.

How can manufacturing software communicate consistently with tightening equipment from different manufacturers?

Open Protocol provides an established industry-standard interface for doing exactly that.

Originally developed by Atlas Copco, Open Protocol has become widely used for communication with tightening equipment on assembly lines. Atlas Copco describes it as a standard communication protocol between tightening controllers and external production systems and notes that it has developed into an industry standard for this purpose.

At Ansomat, Open Protocol is a standard integration within our Operator Guidance System. This allows compatible fastening tools to become part of the guided assembly workflow rather than operating as standalone equipment.

In this guide, we explain what Open Protocol is, how it works, which fastening tools can use it, and how manufacturers can combine Open Protocol with Operator Guidance, torque monitoring, torque angle control, tool positioning and production traceability.

What Is Open Protocol?

Open Protocol is a communication protocol for exchanging information between industrial tightening controllers and external production software.

In an Operator Guidance environment, it creates the communication layer between the assembly workflow and the fastening equipment.

This creates two-way communication:

Operator Guidance → Open Protocol → Tightening Controller → Fastening Tool

and:

Fastening Result → Open Protocol → Operator Guidance

The fastening tool therefore becomes part of the digital assembly process rather than operating as an isolated device.

Why Is Open Protocol Important for Industrial Fastening?

Modern tightening systems can control and measure significantly more than torque.

The challenge is making this information available to the rest of the production system.

Without a common interface, Operator Guidance software may require a separate integration for every fastening-tool manufacturer.

Without standardization:

Operator Guidance → Vendor A interface → Tool A
Operator Guidance → Vendor B interface → Tool B
Operator Guidance → Vendor C interface → Tool C

With Open Protocol:

Operator Guidance → Open Protocol → Compatible tightening controllers

This reduces integration complexity and makes multi-vendor fastening architectures easier to manage.

Which Fastening Tools Can Use Open Protocol?

Open Protocol is not limited to one type of fastening tool.

The protocol generally communicates with the tightening controller, which controls or communicates with the physical tool.

It can therefore be used with different categories of intelligent fastening equipment.

Open Protocol is also increasingly multi-vendor. Manufacturers such as Atlas Copco, STANLEY Assembly Technologies and ESTIC support Open Protocol in parts of their tightening portfolios.

This reflects a wider industry shift: fastening tools are becoming connected components of the digital assembly environment.

Suppliers that rely exclusively on proprietary communication interfaces can require additional engineering, testing and software maintenance. As factories become more connected, interoperability is increasingly an important criterion when selecting industrial fastening tools.

Manufacturers are no longer asking only:

“Does this tool provide the torque, accuracy and ergonomics we need?”

They are also asking:

“How easily can this tool integrate with our digital assembly architecture?”

How Does Open Protocol Work?

Open Protocol exchanges structured messages between the Operator Guidance System and tightening controller.

A typical Ansomat architecture is:

Ansomat Operator Guidance

↓

Open Protocol

↓

Tightening Controller

↓

Electric Torque Tool

The communication works in both directions:

This creates a closed digital loop between the work instruction and the physical fastening operation.

What Are MIDs and Psets?

Two important Open Protocol concepts are MIDs and Psets.

MID

Each Open Protocol message uses a four-digit Message ID.

Different MIDs are used for functions such as communication startup, Pset selection, tightening-result subscriptions, tightening results, identifiers and controller information.

Different MID revisions can support additional functionality, which is why compatibility should always be checked for each tightening controller.

Pset

A Pset contains the parameters required for a particular fastening operation.

These can include:

A product can require different Psets for different joints.

Operator Guidance can automatically select the correct Pset through Open Protocol, eliminating the need for the operator to manually choose the program.

Operator Guidance + Open Protocol

This is where Open Protocol becomes especially valuable.

Traditional digital work instructions tell the operator what to do.

A connected Operator Guidance System can also coordinate the equipment required to perform the operation.

For example:

Step 12 — Tighten Bolt A

Operator Guidance automatically selects the correct Pset and enables the tool.

If the result is:

✓ OK → continue to Bolt B

If the result is:

✕ NOK → stop, retry or start rework

The digital work instruction therefore becomes an interactive production workflow.

Open Protocol as a Standard Ansomat Integration

Open Protocol is a standard integration within the Ansomat Operator Guidance System.

Operator Guidance acts as workstation-level process control software, coordinating what the operator sees with what the connected assembly tools need to do.

This creates a controlled relationship between instruction, tool and result.

Fastening Traceability

Open Protocol also allows tightening information to become part of the product's production record.

This is particularly valuable in automotive, aerospace, battery manufacturing and other industries where critical fastening operations must be documented.

Open Protocol vs Other Communication Methods

Open Protocol is not the only way to connect tightening equipment. These technologies can also work together.

A typical architecture might be:

ERP / MES

↓

OPC UA / APIs

↓

Operator Guidance

↓

Open Protocol

↓

Tightening Controller

↓

Assembly Tool

The MES provides production context, while Operator Guidance manages execution at the workstation.

Practical Example: EV Battery Assembly

Consider an EV battery pack requiring a critical fastening at position B17.

The operator does not need to manually change programs or record tightening results.

Benefits of Open Protocol

Conclusion

Open Protocol provides an established interface for connecting intelligent fastening equipment with Operator Guidance and process control software.

Whether a workstation uses an electric nutrunner, electric screwdriver, digital torque wrench, electronic torque wrench, torque-controlled electric screwdriver or other electric torque tools, the objective is increasingly the same:

Select the correct program → guide the operator → control the tool → monitor torque and angle → validate the result → record the operation → continue production.

Within the Ansomat Operator Guidance System, Open Protocol connects compatible tightening equipment directly to the assembly workflow.

Combined with torque monitoring, torque angle control, tool positioning, projection AR and traceability, it creates a closed-loop fastening process:

Guide → Position → Configure → Tighten → Validate → Record → Continue

Instead of operating as standalone assembly tools, connected fastening tools become integrated components of the digital production process.