SNAP PAC System Architecture and Selection Guide

SNAP PAC System: An Ideal Platform for Industrial Automation and Control Integration

In the field of modern industrial automation, the flexibility, scalability, and reliability of control systems are key factors determining the success of projects. The SNAP PAC system launched by Opto 22 has been widely used in remote monitoring, data acquisition, and industrial control scenarios since its first release in 2007, thanks to its highly integrated hardware and software architecture. This article will provide a comprehensive and in-depth technical analysis of the SNAP PAC system from multiple dimensions, including system architecture, core components, network configuration, I/O module selection, and installation points.

System Overview and Architecture Design

The SNAP PAC system is a highly integrated automation platform, mainly composed of the following three parts:

PAC Project software suite: provides control programming based on flowcharts, HMI development and runtime environment, as well as optional OPC servers, database connection software, and PC based controllers.

SNAP PAC controller: including standalone or rack mounted industrial controllers, supporting RESTful APIs and multiple network protocols.

SNAP I/O modules: covering analog, digital, and serial communication modules, used to connect field devices, sensors, and actuators.

These three parts together form a system capable of handling everything from basic equipment monitoring to complete factory automation. It is worth noting that starting from 2022, due to the discontinuation of some key components, some SNAP PAC components are no longer produced. The document explicitly recommends the use of alternative components, such as replacing the discontinued EB series brain modules with R series controllers.

System Architecture Example and Scalability

The architecture design of the SNAP PAC system is highly flexible, making it easy to implement from small standalone systems to large-scale distributed control systems.

Minimum System Example: Only one rack mounted controller, local I/O, and free PAC Project Basic software are required. The control program (strategy) is developed on a PC and downloaded to the controller for independent operation. The HMI interface is built through PAC Display and can be accessed using the built-in REST API for IIoT data access.

Small system example: Adding distributed I/O units on the basis of the minimum system. Each I/O unit can independently handle functions such as counting, locking, watchdog timer, thermocouple linearization, PID closed-loop control, etc. Even if communication with the main controller is interrupted, local functions can continue to operate.

System expansion method:

Increasing distributed I/O: By adding more I/O processors and modules, analog, digital, and serial modules can be mixed at any location.

Add HMI seats: For multi client access, it is recommended to use OptoOPCServer to efficiently handle communication loads.

Enhance network security and IIoT capabilities: By adding groov EPIC edge programmable industrial controllers, the system's user authentication, device firewall, data encryption, MQTT communication, and mobile HMI capabilities can be significantly improved.

Accessing enterprise databases: Groov EPIC can easily exchange data with local or cloud databases and software services.

Integrated third-party system: Supports Modbus/TCP, EtherNet/IP, DF1 protocol, and provides RESTful API for developers to access tag data in the controller using any programming language.

Detailed explanation of core component selection

1. Software selection

The SNAP PAC system offers two versions of software suites:

PAC Project Basic (free): includes PAC Control (control programming), PAC Display (HMI development), and PAC Manager (configuration and diagnostics). Suitable for most standard monitoring applications.

PAC Project Professional (paid): adds OptoOPCServer (OPC 2.0 communication), OptoDataLink (ODBC database connection), and SoftPAC (PC based software controller) on the basis of Basic. In addition, Ethernet link redundancy and controller redundancy are also supported (note: controller redundancy function is no longer supported for new projects, and related hardware has been discontinued).

2. Controller selection

SNAP PAC R series (rack mounted): directly installed on the I/O rack, integrating I/O processing and control functions. The R1 model supports high-speed digital function, while the R2 model does not have high-speed digital function. Suitable for unit control or small-scale distributed systems. Support RESTful API.

SNAP PAC S series (standalone): With stronger performance, it can run up to 64 PAC Control flowcharts simultaneously (32 for R series). S1 provides 1 RS-485 and 2 RS-232 serial ports; S2 provides four software configurable serial ports for RS-232 or RS-485. Support communication with legacy Mistic serial I/O units (requires PAC Project Professional).

SoftPAC (PC based): A software controller running in the Windows environment, suitable for scenarios that require large amounts of file storage, mathematical calculations, or running multiple flowcharts simultaneously. Only supports Ethernet communication and does not support serial I/O units.