# Modbus Implementation Overview

The Modbus Plugin provides the following features for Cognex Designer:

- Client and server communication with external hardware using the Modbus TCP Protocol.
- Support of Modbus IO Functions defined in the Modbus Protocol.
- Sending Modbus messages using Modbus Task Blocks or Scripting.
- Sending success and failure messages with script points and Task Mode triggers.
- Ability to map software-based Modbus storage to tags.

The Modbus Plugin uses the third-party NModbus4 open source library, which is an implementation of the Modbus protocol.

Note:

The Cognex Designer Modbus Plugin is a software-based implementation over the TCP/IP port, and not a hardware-based solution through the PLC port found on Cognex communications hardware (such as the Cognex VC5 Vision Controller or the CC24 Cognex Communication Card). As such, communication performance (such as throughput, speed, latency, or response time) highly depend on the following factors:

- The underlying hardware.
- The software environment.
- The capabilities of the lower network layers and network devices.

Because of this, latency might occur that might be unacceptable for high-speed applications. Therefore, if your application requires more predictable external performance, develop communications between Cognex Designer and other hardware using one of the supported hardware-based PLC communication protocols (such as PROFINET or SLMP) available for Cognex Designer.