OPC UA Server Performance

Overview

As an example, the following provides capacity and performance information for the OPC UA server of the M262 Logic Controller. Design considerations are also provided to help you consider the optimal conditions for the performance of the OPC UA server. Of course, the performance realized by your application depend on many variables and conditions, and may differ from this example.

NOTE: These values are only valid if the OPC UA client function is not used.

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 small and medium configurations used for evaluating OPC UA server performance:

Elements

Small

Medium

TM3 expansion modules

0

4

CANopen slave devices

0

0

PTO functions

0

0

HSC functions

0

0

Profibus connections

0

0

Modbus TCP slave devices

0

0

Sercos devices

0

0

Incremental hardware encoders

0

0

Serial lines

0

1

EtherNet/IP adapters

0

1

EtherNet/IP Scanner devices

0

18

Generic TCP/UDP Managers

0

0

This table presents average read/write request times for the sample configurations and for different numbers of symbols:

Average Read/Write Request Times

Configuration

Number of Symbols

50

100

250

400

500

1000

TM262L10MESE8T

Small

6 ms

11 ms

26 ms

41 ms

53 ms

132 ms

TM262L10MESE8T

Medium

16 ms

29 ms

71 ms

117 ms

149 ms

350 ms

TM262L20MESE8T

Small

3 ms

5 ms

12 ms

18 ms

23 ms

56 ms

TM262L20MESE8T

Medium

14 ms

23 ms

51 ms

80 ms

103 ms

123 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

TM262L10MESE8T

Small

204 ms

207 ms

218 ms

TM262L10MESE8T

Medium

197 ms

209 ms

680 ms

TM262L20MESE8T

Small

201 ms

203 ms

201 ms

TM262L20MESE8T

Medium

202 ms

205 ms

215 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

TM262L10MESE8T

Small

203 ms

204 ms

208 ms

TM262L10MESE8T

Medium

195 ms

201 ms

623 ms

TM262L20MESE8T

Small

201 ms

202 ms

204 ms

TM262L20MESE8T

Medium

202 ms

203 ms

207 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

TM262L10MESE8T

Small

201 ms

202 ms

202 ms

TM262L10MESE8T

Medium

194 ms

196 ms

285 ms

TM262L20MESE8T

Small

200 ms

201 ms

201 ms

TM262L20MESE8T

Medium

201 ms

202 ms

202 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.

 WARNING
UNINTENDED EQUIPMENT OPERATION
  • Do not allow safety-related data in OPC UA server data exchanges.
  • Do not use OPC UA server data exchanges for any critical or time-dependent purposes.
  • Do 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.

To optimize OPC UA server performance, consider the following:

  • Minimize Ethernet traffic by setting the Min. publishing interval to the lowest value that yields an acceptable response time.

  • The task cycle time configured for the controller must be less than the configured Min. publishing interval value.

  • Configuring 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.

  • The 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 controller.