1. Genius Webinar series, August 2013
Troubleshooting OPC
Genius Webinar series, August 2013

2. Goals of today’s training
Give an overview of OPC architecture
Define OPC roles
Review some troubleshooting techniques
Cover some common problems and solutions
You should be positioned to solve 80-90% of OPC errors

3. What is OPC? Let’s define the acronym
Originally meant “OLE for Process Control”
In November of 2011, the OPC Foundation officially renamed it to mean “Open Platform Communications”.
Let’s define our scope
There are many OPC standards
OPC Alarms & Events
OPC Batch
OPC Historical Data Access
…and many others
We are only talking about OPC Data Access 2.0a today. There are no Rockwell products that use these other standards.

4. Proprietary Communication
Why OPC?
In olden times, applications had their own built-in drivers.
Example: AdvisorPC, ControlView
Disadvantage: when new devices appeared, product had to go through the entire product release cycle.
Application Software
With
Proprietary Communication
Drivers

5. OPC protocol defined by OPC Foundation
Why OPC?
Eventually vendors found it easier to create “data servers”.
Much less effort to make changes to comms.
Original standard was Microsoft’s DDE protocol, part of Microsoft Office suite.
Over time, data acquisition needs outgrew DDE’s capacity. The OPC Foundation was formed and the OPC standard was introduced.
OPC Server
OPC protocol defined by OPC Foundation
OPC Client #1
OPC Client #2
See for lists of servers

6. OPC Architecture OPC consists of: Clients Servers OPC
Middleman between clients and control devices
Optimizes data requests
Talk to servers
Examples: SE, FTTM, RSView32, 3rd-party HMI

7. Good Troubleshooting Techniques
Divide and conquer
Check connection between OPC server computer and processor.
Ping (for Ethernet networks)
RSWho
Data Monitor (available through right-click on processor)
If practical, connect OPC server directly to processor.
Check connection between OPC client and OPC Server
Get a 2nd opinion: can a different OPC client connect (OPC Test Client, Rockwell Software Data Client)?
If client is on a remote computer, try running it on the server.

8. Good Troubleshooting Techniques
Go to the source (the OPC server)
Communication servers are in best position to know what the error is.
RSLinx diagnostics are your friend.
DDE/OPC--> Communication Events.
DDE/OPC--> Active Topics/Items.
Check the knowledgebase for information on these errors.
RSLinx Classic: OPC/DDE Communication Event Log Error Messages
Others as well.

9. Common Communication Problems

10. List of Common Problems
Topic not configured properly.
Processor not connected / powered up.
Wrong program loaded.
Too much traffic (network or processor).
Firewall blocks connection to the OPC server.
RSLinx Classic is not activated.
Bad address in packets cause problems for other good addresses.

11. Topic not configured properly
Causes:
Topic points to something other than a controller (workstation?)
Topic has the wrong device type specified
Name is spelled wrong
Identification:
When clicking on topic, controller is not highlighted
Communication event log contains errors like:
This is an undefined topic. Verify the topic is in the current project.
When loading this topic, it was not possible to resolve the target path that is part of the topic's configuration
Best Practice: Let RSLinx create topic using the right-click method!

12. Processor not connected / powered up.
Causes:
Controller is turned off.
Cable is disconnected.
Identification:
Walk over to the chassis and look.
Ping (if using Ethernet)
See if device shows up in RSWho

13. Wrong program loaded Causes: Someone downloaded the wrong program.
Controller may have no program (faulted).
Topic points to wrong controller
Identification:
Go online and verify the program is correct (also Data Monitor).
Check to see if processor has any faults or LEDs.
Double-check address and type of processor.

14. Too much traffic (network or processor).
Causes:
Controller is busy (ladder, MSG, periodic tasks, etc).
Network is busy (too many requests and too fast).
Identification
Putting controller in Program mode solves problem (bottleneck is the controller).
Limiting Maximum Packets in topic fixes the problem (bottleneck is network or controller).
Check communication log for “application layer timed out…”

15. Firewall blocks connection
Causes:
Someone undoes the changes made to Windows Firewall.
(More likely) A 3rd-party firewall has been installed or hardware firewall is blocking ports.
Identification:
OPC Test Client fails when selecting the server.
RSLinx Classic DDE/OPC--> Active Topics/Items shows no topics are active.
See TCP/UDP Ports Used by Rockwell Automation Products for a list of relevant ports.

16. RSLinx Classic is not activated
Causes:
No activation was purchased.
Wrong activation (remote clients required Gateway license).
Activation was corrupt.
Note – no activation is required for FactoryTalk View SE or ME to connect to RSLinx Classic. However other OPC or DDE clients still required this activation. So RSView32 would not be able to communicate to RSLinx Lite.
Identification:
RSLinx title bar shows “RSLinx Lite”
Clients try to connect to “Remote RSLinx OPC Server” but no RSLinx Gateway activation is present.

17. Bad addresses in packet
Cause:
At least 1 non-existent addresses is in the same packet as other good addresses
Identification:
Common behavior: Clients seem to work initially but stop working as more screens are opened.
RSLinx communication event log contains “tag or item does not exist”.
OPC Test Client can see the data but other clients cannot (this could also be caused by other things).

18. Summary
Always use “Divide and conquer” to narrow the scope of the problem.
Take advantage of communication event log and other diagnostics.
Be sure to check the knowledgebase for details on specific errors.
Get a 2nd opinion using the OPC Test Client
Questions?