Low-cost PAC Redundancy

In China, “you can’t even bid on a project unless you can check the box that you have redundancy,” says Benson Hougland, Opto 22 vice president, marketing.

It was out of that need that one of the company’s newest products was born. The Opto 22 Snap PAC Redundancy Option Kit (Snap-PAC-ROK), unveiled on March 29, can be used to design an Ethernet-based redundant control system with maximum reliability and distributed intelligence that can instantly recover from failure, the company says.

使用标准的Opto 22 S系列SNAP PAC，SNAP以太网I/O和新的PAC Project Professional 9.0软件套件，客户可以使用SNAP PAC冗余选项套件来配置具有基本上同步和并行运行的双PACS的自动化系统。如果一个控制器失败或被撞倒，则另一个控制器将承担命令并继续执行控制程序及其运行的过程，而无需中断或重新启动。

When compared to other redundancy approaches on the market, one big advantage of the ROK solution is its price, according to Hougland. While competitive solutions often require expensive, high-end or specialized controllers to achieve redundancy, the ROK works with two standard S-series Snap PACs, priced at around $1,500 each, Hougland says. Communication is over Ethernet using standard Cat 5 cabling. No proprietary communication protocols, interfaces or custom cables are required.

Redundant Opto 22 control systems created with the Snap PAC ROK provide various advantages for users. For instance, the two identically configured controllers (active and back-up) are able to swap roles in the redundancy scheme at any time, offering flexibility and other benefits during system start-up and commissioning. Redundancy advantages also include a significant reduction in the control system’s mean time between failures (MTBF), and thus even greater levels of reliability for process-oriented applications.

Components of the Snap PAC Redundancy Option Kit include:
• A Redundancy Arbiter—a standalone processor that connects serially to both controllers and monitors and regulates their status and maintains synchronization of the control program during system startup
• A Redundant Power Switch, which allows power re-starts to controllers in the event of failure and during firmware upgrades.

The PAC Redundancy Manager, a software utility for configuring redundant systems, including IP addresses, program synchronization and firmware matching, is included in PAC Project Professional 9.0. This utility is also used for maintaining and monitoring a functioning system.

该公司表示，对冗余控制器的支持也许是Opto 22的PAC Project 9.0软件中最令人期待，最有力的新功能。PAC Project 9.0也于3月29日宣布，是一套完整的软件应用程序和实用程序，可提供控制编程，HMI开发，OPC连接，数据库集成，与Allen-Bradley Logix系统的通信以及对控制器冗余的支持。

www.opto22.com