UM-0085-B09
DT80 Range User Manual
Page 170
RG
Customising the Classic Interface
This section describes some of the technical features of the
DT80
web interface. These allow advanced users to replace
the built-in web interface with a customised web user interface.
Web Application Programming Interface (API)
The
DT80
provides an application programming interface (API) so that you can build custom web pages that can view
and display data from the logger. The API consists of a set of
server-side include
(SSI) directives. SSI directives are
placed in HTML pages, and evaluated on the logger when the HTML page is requested. HTML pages that contain SSI
directives are known as
SHTML
pages, and typically have a
.shtml
file extension.
When an SHTML page is requested, it is scanned by the web server (logger) for these directives. Once found, the logger
interprets the directive and performs the required action. The output is then sent as part of the response back to the web
browser.
Server-Side Include (SSI) Directives
An
SSI directive
consists of a special sequence of characters which is placed within an HTML page. The format is as
follows:
<!--#
directive
attribute
="
value
"
attribute
="
value
"
…
-->
where:
•
<!--#
and
-->
are the opening and closing identifiers that must be specified when applying an SSI directive.
•
directive
is the name of the directive to be executed.
•
attribute
is the name of an
attribute
, and
value
is the value it is set to. Each SSI directive has a set of valid
attributes that can be specified to control the operation of the directive. One or more attribute-value pairs can be
specified.
For example
<!--#echo var = "1CV" -->
inserts the SSI directive named
echo
, which contains one attribute
var
whose value is set to
1CV
.
DT80 SSI Directives
The
DT80
web server supports five SSI directives, which are summarised in the table below. Each directive requires the
indicated attribute to be set. In addition, one or more optional attributes may be included.
Directive
Required Attribute
Function
echo
var
Inserts the current value of the indicated variable
channeltable schedule
Inserts an HTML table containing, for each channel, its schedule, name, most recent
value, units and timestamp – similar to the
Channels
page
measure
channel
Samples the indicated channel (certain channel types only) and inserts the measured
value
reading
channel
Inserts the most recent value of the indicated channel, plus timestamp
include
file
or
Inserts the contents of the indicated text file, specified as a path relative to the
document root (
DOC_ROOT
profile setting
virtual
Inserts the contents of the indicated text file, specified as an absolute path
Optional Attributes
One optional attribute is supported, which may be applied to any of the above directives in addition to their standard
attribute:
Directive
Attribute
Function
any
cond
Evaluate the directive if and only if the indicated condition is true
The following sections discuss each directive in more detail.