Issue:
Machine SCADA Expert uses two types of driver sheets for communication:
- MAIN DRIVER SHEET
Automatically created when adding a communication driver.
Note: Not all drivers include a MAIN DRIVER SHEET.
- STANDARD DRIVER SHEETS
Additional sheets that provide additional fields that can be used to control communication.
Polling speed depends on:
- Number of variables
- Protocol characteristics
- PLC performance
- Worksheet scan rate
- Simultaneous requests configured in SCADA
This FAQ covers the methods available in Machine SCADA Expert to try to improve the polling rate of the variables configured in the MAIN DRIVER SHEET and the STANDARD DRIVER SHEETS.
Product:
EcoStruxure Machine SCADA Expert v2020, v2023
Environment:
HMI Configuration Software in Windows
Resolution:
Method 1: Reduce Worksheet Scan Rate
- MAIN DRIVER SHEET
The Machine SCADA Expert project by default will scan the communication worksheets every 600 milliseconds; therefore, a way to receive updates from values faster is by reducing this worksheet scan rate time set up by the software.
To do this, we need to manually adjust it by editing the project file <project name>.APP using a text editor software, and then add the following entry under [Options]:
MainDrvAlwaysTrigger=tagname
And replace tagname with a tag that will change at the desired interval.
Example:
a. Polling rate of one tag using the default scan rate (600ms):
b. Polling rate of one tag with a defined scan rate (100ms):
Note: To create a tag that will change periodically as we desired, we need to use the "Scheduler" task, please check FAQ: FAQ000272116 .
Note: The "scanrate100" tag was added to the log list of the Output window, so the polling rate can be seen.
Keep in mind that in this example only one tag is being read. If reading several tags, the scan rate displayed can vary. There are also other factors that affect this, as explained at the beginning of this FAQ.
Related resources:
From: EcoStruxure™ Machine SCADA Expert , Help Manual - 07/2024 - P.522
Title => "EcoStruxure™ Machine SCADA Expert, Help Manual"
- STANDARD DRIVER SHEETS
For the STANDARD driver sheets the scan rate will depend in the tag defined in the Read/Write Trigger:
Example:
a. Using the created tag scanrate100 that changes every 100ms.
b. Setting to TRUE the field Enable Read when idle:
Note: This is only true in this example with just one tag, having more tags will increase the polling time.
Related resources:
From: EcoStruxure™ Machine SCADA Expert , Help Manual - 07/2024 - P.523,524
It is also recommended to read P.525
Method 2: Increase Simultaneous Requests
Another way to improve the scan polling rate of the driver tags is by modifying the number of simultaneous requests in the driver configuration and checking if there is an improvement. You can start with 2-2, and if there is an enhancement, increase it to 4-4. If you have more PLCs using this driver, apply a similar approach, where 12-4 means 12 maximum simultaneous requests and 4 maximum per station.
Example:
- Right click in the driver folder and click in Settings
- Click in Advanced
- Adjust the Simultaneous Requests
If you set too many simultaneous requests, it may overload the PLC. Be conservative with this number and consider the capabilities of your PLC.
Related resources:
EcoStruxure™ Machine SCADA Expert, Help Manual - 07/2024 - P.517
