Web server
12.7 User-defined Web pages
S7-1200 Programmable controller
1068 System Manual, V4.2, 09/2016, A5E02486680-AK
Writing a special variable
The "Remote Wind Turbine Monitor" Web page writes the special variable
SERVER:current_user_id to a PLC tag in the CPU, providing that the user has modify
privileges. In this case, the PLC tag value contains the user ID of the user who is accessing
the "Remote Wind Turbine Monitor" Web page.
The Web page writes the special variable to the PLC and requires no user interface.
<!-- AWP_In_Variable Name="SERVER:current_user_id" Use="User_ID"-->
Reference: HTML listing of remote wind turbine monitor Web page
Wind_turbine.html
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<!--
This test program simulates a Web page to monitor and control a Wind
Turbine
Required PLC tags and Data Block Tags in STEP 7:
PLC Tag:
User_ID: Int
Data Blocks:
Data_block_1
Tags in Data_Block_1:
TurbineNumber: Int
WindSpeed: Real
WindDirection: Real
Temperature: Real
PowerOutput: Real
ManualOverrideEnable: Bool
TurbineSpeed: Real
YawOverride: Bool
Yaw: Real
PitchOverride: Bool
Pitch: Real
Braking: Real
The user-defined Web page displays current values for the PLC data,
and provides a select list to set the three Booleans using an
enumerated type assignment. The "Submit" button posts the selected
Boolean values as well as the data entry fields for TurbineSpeed,
Yaw, and Pitch. The value for Braking can be set without use of the
"Submit" button.
No actual STEP 7 program is required to use this page.
Theoretically, the STEP 7 program would only act on the values of
TurbineSpeed, Yaw, and Pitch, if the associated Booleans were set.
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