Using An Enum Type - Siemens SIMATIC S7-1200 System Manual

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12.7 User-defined Web pages

Using an enum type

The "Remote Wind Turbine Monitor" HTML page uses enum types for the three instances

where HTML page displays "ON" or "OFF" for a Boolean value, and for where the user sets

a Boolean value. The enum type for "ON" results in a value of 1, and the enum type for

"OFF" results in a value of 0. For example, consider the HTML code for reading and writing

the Manual Override Enable setting in "Data_block_1".ManualOverrideEnable value using an

Example HTML code

The following excerpts from the "Remote Wind Turbine Monitor" HTML page show how to

declare an enum type called "OverrideStatus" with values of "Off" and "On" for 0 and 1, and

then setting an enum type reference to OverrideStatus for the ManualOverrideEnable

Boolean tag in the data block named "Data_block_1".

<!-- AWP_In_Variable Name='"Data_block_1".ManualOverrideEnable'

Enum="OverrideStatus" -->

Where the HTML page includes a display field in a table cell for the current state of

ManualOverrideEnable, it uses just a normal read variable command, but with the use of the

previously declared and referenced enum type, the page displays "Off" or "On" rather than 0

<td style="width:24%; border-top-style: Solid; border-top-width:

2px; border-top-color: #ffffff;">

<p>Manual override: :="Data_block_1".ManualOverrideEnable:</p>

The HTML page includes a drop-down select list for the user to change the value of

ManualOverrideEnable. The select list uses the text "Yes" and "No" to display in the select

lists. With the use of the enum type, "Yes" is correlated to the value "On" of the enum type,

and "No" is correlated to the value "Off". The empty selection leaves the value of

ManualOverrideEnable as it is.

The select list is included within a form on the HTML page. When the user clicks the submit

button, the page posts the form, which writes a value of "1" to the Boolean

ManualOverrideEnable in Data_block_1 if the user had selected "Yes", or "0" if the user had

selected "No".

S7-1200 Programmable controller

System Manual, V4.2, 09/2016, A5E02486680-AK