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Getting spot prices with WattPrice driver
Mervis system can get spot prices of electrical energy. This functionalty is available only for Patron and Gate units.
Warning:
Currently, getting prices is available only for Czech region. See czech translation of this page for up to date infromation.
Attetion:
Due to format changes in messages from API. It is no longer possible to read currecnt prices in IDE 2.6.5.
Communication using WattPrice protocol is available from version Mervis IDE 2.7.6 and after updating the .NET server. This IDE version is distributed directly by Mervis developers on their site.
Tutorial on how to update the .NET driver can be found at .Net Server pro MErvis RT.
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Enabling drivers in PLC configuration
To get the driver up and running, you have to enable the .NET server in PLC configuration, in the Common Properties section, enable the Enable .NET drivers items. Configuration shall be uploaded to the PLC now.
Adding a channel and device
Right-click on the PLC and select Add channel:
We click on newly created channel and in its properties we set Protocol to Watt Price (.NET):
We right-click on the channel and select Add Library Device:
Select the device:
- Watt Price 15-Minute Period (Array) – data will be in an array
- Watt Price 15-Minute Period (Variables) – data will be as individual variables
Device properties
Properties of the device has to remain original, only following may be changed:
- Cache Timeout – timeout, after data will be updated
- Date Shift Days – shifts the data by a day (use value 1 for next day)
Datapoints
The driver provides following information for the Czech region:
- PriceInQH [real] – variables or array with prices for every interval
- QuarterHoursInDay [int] – number of quarter hours of the day (summer and winter shift cause different counts)
- PriceMinimum [real] – minimal price of the day
- PriceMaximum [real] – maximal price of the day
- PriceAverage [real] – average price of the day
- PriceCurrent [real] – actual price
