
B Description of the PROFINET Configuration File
The Cycle Time Parameter
This parameter will be configured in the user interface as of SIMATIC NET V6.1 with STEP 7/SIMATIC NCM PC V5.2 and higher.
Parameter | Meaning |
|
|
Syntax | [PROTOCOL] |
| CycleTime=100 |
|
|
Purpose | The scan cycle time specifies how often the OPC |
| server updates the values of the OPC items using |
| a new communication job. |
|
|
Default | 100 ms |
|
|
Relationship between Cycle Time and Update Rate | The “UpdateRate” parameter that can be set in the |
| user program specifies the shortest possible |
| interval for checking the values of the OPC items of |
| an active OPC group. When this interval elapses, |
| the server checks whether or not the values of the |
| active OPC items have changed. |
| The update rates used by the OPC Server for |
| SIMATIC NET are multiples of the cycle time |
| specified here during project engineering. The |
| maximum update rate (shortest interval) is the |
| same as the cycle time. |
|
|
Relationship between the Set | Since the SIMATIC NET OPC Server can use |
Cycle Times | variables of different protocols at the same time, |
| the maximum update rate of the OPC server is the |
| highest value set for the scan cycle time for the |
| active protocols (those for which connections are |
| configured). |
|
|
Example | A scan cycle time of 100 ms is configured for |
| PROFInet. No other protocol is being used. 100 ms |
| is used by the OPC server as the minimum update |
| interval. The S7 protocol is now added and the |
| scan cycle time configured for this protocol is 500 |
| ms. Result: The OPC Server now uses the value |
| 500 ms as the minimum update interval for all |
| protocols. |
|
|
288 | Commissioning PC Stations - Manual and Quick Start |
Release 5/2005 |
C79000- G8976- C156 - 07