The following provides capacity and performance information for the OPC UA server of the M241 Logic Controller. Design considerations are also provided to help optimize the performance of the OPC UA server.
System Configurations Used to Evaluate Performance
OPC UA server performance is determined by the system configuration, the number of symbols being published, and the percentage of symbols being refreshed.
The following table presents the number of elements in small, medium, and large sample configurations used for evaluating OPC UA server performance:
|
Elements |
Small |
Medium |
Large |
|---|---|---|---|
|
EtherNet/IP adapters |
0 |
7 |
0 |
|
Expansion modules |
0 |
5 |
7 |
|
CANopen slave devices |
0 |
1 |
63 |
|
PTO functions |
0 |
4 |
4 |
|
HSC functions |
0 |
8 |
8 |
|
Profibus connections |
0 |
0 |
1 |
|
Modbus TCP slave devices |
0 |
6 |
64 |
This table presents average read/write request times for each of the sample configurations and for different numbers of symbols:
|
Average Read/Write Request Times |
||||||
|---|---|---|---|---|---|---|
|
Configuration |
Number of Symbols |
|||||
|
50 |
100 |
250 |
400 |
500 |
1000 |
|
|
Small |
42 ms |
70 ms |
151 ms |
232 ms |
284 ms |
554 ms |
|
Medium |
73 ms |
121 ms |
265 ms |
412 ms |
514 ms |
1024 ms |
|
Large |
520 ms |
895 ms |
2045 ms |
3257 ms |
4071 ms |
7153 ms |
The following tables present the average time required to refresh a monitored set of symbols using a sampling rate of 200 ms and a publishing interval of 200 ms.
This table presents the average time required to refresh 100% of symbols for each of the sample configurations:
|
Average Time to Refresh 100% of Symbols |
|||
|---|---|---|---|
|
Configuration |
Number of Symbols |
||
|
100 |
400 |
1000 |
|
|
Small |
214 ms |
227 ms |
254 ms |
|
Medium |
224 ms |
250 ms |
292 ms |
|
Large |
234 ms |
330 ms |
800 ms |
This table presents the average time required to refresh 50% of symbols for each of the sample configurations:
|
Average Time to Refresh 50% of Symbols |
|||
|---|---|---|---|
|
Configuration |
Number of Symbols |
||
|
100 |
400 |
1000 |
|
|
Small |
211 ms |
220 ms |
234 ms |
|
Medium |
219 ms |
234 ms |
254 ms |
|
Large |
284 ms |
300 ms |
660 ms |
This table presents the average time required to refresh 1% of symbols for each of the sample configurations:
|
Average Time to Refresh 1% of Symbols |
|||
|---|---|---|---|
|
Configuration |
Number of Symbols |
||
|
100 |
400 |
1000 |
|
|
Small |
210 ms |
210 ms |
212 ms |
|
Medium |
215 ms |
217 ms |
220 ms |
|
Large |
270 ms |
277 ms |
495 ms |
Optimizing OPC UA Server Performance
The OPC UA server functionality is dependent on external communication networks, external device performance, and other external parameters. Data transmitted may be delayed or other possible communication errors may arise that impose practical limits on machine control. Do not use the OPC UA server functionality for safety-related data or other time-dependent purposes.
|
|
|
UNINTENDED EQUIPMENT OPERATION |
|
oDo not allow safety-related data in OPC UA server data exchanges. oDo not use OPC UA server data exchanges for any critical or time-dependent purposes. oDo not use OPC UA server data exchanges to change equipment states without having done a risk analysis and implementing appropriate safety-related measures. |
|
Failure to follow these instructions can result in death, serious injury, or equipment damage. |
The above tables can be useful in determining whether OPC UA server performance is within acceptable limits. Be aware, however, that other external factors influence overall system performance, such as the volume of Ethernet traffic, or the use of jitter.
To optimize OPC UA server performance, consider the following:
oMinimize Ethernet traffic by setting the Min. publishing interval to the lowest value that yields an acceptable response time.
oThe task cycle time configured for the M241 Logic Controller must be less than the configured Min. publishing interval value.
oConfiguring a Max. number of sessions (the number of OPC UA clients that can simultaneously connect to the OPC UA server) value of greater than 1 decreases the performance of all sessions.
oThe sampling rate determines the frequency at which data is exchanged. Tune the Sampling rates (ms) value to product the lowest response time that does not adversely affect the overall performance of the logic controller.
