Re: [EXTERNAL] EPICS PLC5 Support

["Hartman, Steven via Tech-talk" <tech-talk at aps.anl.gov>]

Hi Josh and welcome to the community. Some of your questions are difficult to answer definitively but I’ll offer my view. EPICS has been used successfully in industrial control systems, but its primary use is in experimental science facilities. 

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Hi Josh and welcome to the community. Some of your questions are difficult to answer definitively but I’ll offer my view.

EPICS has been used successfully in industrial control systems, but its primary use is in experimental science facilities. Some of the strengths of the EPICS toolkit relate to the special needs of these facilities. EPICS supports a highly heterogeneous hardware environment including industrial controllers like PLCs, scientific instrumentation, and custom electronics. It is a toolkit which allows you to develop customized solutions, which is important because each of these scientific facilities is essentially one-of-a-kind. It is highly reconfigurable which enables these facilities to add new capabilities. It is highly scalable with implementations of systems with thousands of process variables to systems with millions of process variables. It is a highly distributed control system which enables evolution over the several decade long lifetime of these facilities. And EPICS is open source with a community of users working in environments with similar needs. 

To your specific questions . . .

1.  I don’t think any control system can claim to run “indefinitely" with no outages. But EPICS core and commonly used modules are very stable and robust. I have seen embedded IOCs (the servers) with uptimes measured in years. In practice, the uptime is typically limited by need to change functionality or add new capabilities, or by hardware problems including power outages, or by the need to patch or update the host operating system. Specific uptime needs can be addressed by the system architecture to accommodate planned outages, and reasonable response to unplanned outages. 

2. I have no experience with Reach Automation Studio, but my experience with CS-Studio is that it has good stability for a client application. But note that, unlike the IOCs (the servers), the clients like CS-Studio do not need to be always up for the control system to be operational. As a highly distributed control system, there can be 0 to very many instances of CS-Studio running at any given time without impacting the operation of the underlying control system. 

3. As a distributed control system, you can have many IOCs connected to many devices serving many channels. At SNS, ether_ip is used to communicate with >100 PLCs with a total of 100s of thousands of IO points. However, the distributed “physical sites” may be an issue. With the SNS example, those PLCs are in multiple buildings but are all on a common private network. EPICS is not appropriate to be run on an open network. Tunneling over ssh, for example, is possible but I do not have any practical experience with that. 

4. ether_ip supports the ControlLogix and CompactLogix families of PLCs. It has not be demonstrated to work with any other PLC. In the ~1990s, there was an EPICS interface to the AB PLC5 but I do not know if it is still in active use anywhere and the hardware required is long obsolete. You would need to migrate to the ControlLogix or Compact Logix, or perhaps use that as a bridge to your older PLC5. 

5. As Ralph mentioned, there is active development to add encryption to the PVAccess protocol. EPICS has typically been run on isolated networks and is not appropriate for internet-facing installations. 

Regards,

-- 

Steven Hartman

hartmansm at ornl.gov

On Feb 22, 2024, at 9:44 AM, Josh West via Tech-talk <tech-talk at aps.anl.gov> wrote:

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Good Morning,

                I am evaluating the use of EPICS in a non-physics/laboratory industrial control system. The control system requires exceptional stability and reliability and primarily interfaces PLCs and RTUs on an ethernet network. The system also requires support for some aged equipment (Allen-Bradley PLC5).

 

1. Is the current build stable enough to run indefinitely with no EPICS-caused outages?
2. Is Control System Studio or React Automation Studio stable and reliable similar to question 1?
3. Can the ether_ip module support greater than 10K points distributed across multiple PLCs and physical sites?
4. Has anyone successfully deployed a module to support Ethernet/IP interface with an Allen-Bradley PLC5 processor?
5. Are there any plans/projects to implement more stringent information security mechanisms into the system (e.g., something consistent with NIST, IEC, etc. for critical infrastructure)?

 

I have done a thorough review of the mailing list, EPICS training materials, and data I could find through internet searches. I was not able to find much in the way of PLC 5 support. I believe the best current answer is to install an Allen-Bradley MicroLogix Controller as an intermediate device and forward PLC5 data via the MicroLogix controller and the ether_ip module.  I have also implemented a build in a test environment to prove general functionality, but I do not have a good feel how the system would scale. I am very excited by what I perceive the capabilities of this system to be, and I think it could easily replace a very large, closed source, and expensive software suite we have in production today.

 

V/R

 

Joshua West

Lower Colorado River Authority | Control Systems Administrator