Dear All,

I am new in this forum. Thanks that you give me this opportunity to post my question.

Actually we would like to develop a process control system that meets SIL 3 rating and that is based on IEC 61508/IEC 61511. We would like to have a Redundant, safe and open system. That means if one PLC/PAC is from company x and other is from company N, they must be able to communicate on some open network without any additional hardware. They have to be SIL level 3 certified and offer IEC 61131-3. It must be portable and we must be able to convert and use it from one controller to other controller via OPC. We also need one SCADA. I would be grateful for any information on this forum.

Regards,
Hood

 

Hello Hood,

Very interesting definition for a safety system. This is the first time I see a requirement for two different suppliers of control systems, partners in controling the same safety application. Normally, each manufacturer provides both the safety hardware and the redundancy elements required to build redundant safety applications: For example, Siemens uses S7-400-F/H CPUs, Rockwell provides a "Safety partner" for high-availability.

If I had to work on the BOM for your system, I would look into these providers I know and have worked with; they both offer products that can be certified to SIL3 (IEC 61508) and Cat4 (EN 954-1).

Siemens S7 Distributed safety:
http://support.automation.siemens.com/WW/view/en/12489997
Uses S7-300 and S7-400 Safety CPUs (F-CPUs) and safety I/O (F-I/O), programmed with standard Step 7 software plus S7-Distributed Safety package for configuration, programming and certification of safety functions. Can be certified to SIL3 (IEC 61508) and Cat4 (EN 954-1).

Rockwell GuardLogix:
http://www.rockwellautomation.com/products/certification/safety/pdf/1756UM020AENP_UserMan.pdf
Uses specialized Controllogix CPUs and Safety I/O modules, programmed with RSLogix 5000 software in a dedicated Safety Task.

Normally, Rockwell processors have Ethernet/IP, ControlNet or DeviceNet as innate comm. networks. However, Safety Communications are supported over Profibus-DP, and both Prosoft and SST have Controllogix Profibus scanners that work extremely well with the Controllogix platform. Siemens, of course supports Profibus-DP opn their CPUs; but in this case it would be better to use a separate Communication porcessor for Profibus-DP. Safety comms iover profibus require that both partners be setup as DP-masters, linked together through a special slave called a DP/DP coupler. This is a module that has 2 DP interfaces, holds 2 DP addresses, and is configured as a slave on both partners' master network. What is written by the Controllogiox master to the DP/DP coupler is read by the Siemens master, and vice-versa; it acts as a mailbox interface between both networks. More details are available on the Distributed Safety manual I pointed out earlier.

Both these PLC platforms have OPC servers available, either from the manufacturers directly, or through third-party providers, such as Kepware or Matricon.

Hope this helps,
Daniel Chartier