Experimental Physics and
Industrial Control System

Pete Jemian via Tech-talk <tech-talk at aps.anl.gov> · Tue, 15 Nov 2022 21:58:30 -0600

Your challenge when writing or replacing a PV value into an xml file is locating _which_ PV value to be replaced, finding the correct  the xml node to be edited.  Assuming the XML file uses more than a single PV, you'd need a way of finding the correct one.

That complicates the simple example you request.  For example, one of the widgets in the synApps/std timer screen has this xml:

  <widget type="choice" version="2.0.0">
    <name>choice button #23</name>
    <pv_name>$(P)timer$(N):Go</pv_name>
    <x>5</x>
    <y>34</y>
    <width>70</width>
    <height>35</height>
    <background_color>
      <color red="115" green="223" blue="255">
      </color>
    </background_color>
    <horizontal>false</horizontal>
    <border_alarm_sensitive>false</border_alarm_sensitive>
    <items>
      <item>Item 1</item>
      <item>Item 2</item>
    </items>
  </widget>

The .bob file has these PVs:

(base) ~$ grep pv_name /usr/local/epics/synApps6.1/support/std-R3-6-2/stdApp/op/bob/autoconvert/timer.bob
    <pv_name>$(P)timer$(N):elapsedSecs</pv_name>
    <pv_name>$(P)timer$(N):Go</pv_name>

You could use the findall() (https://lxml.de/tutorial.html#elementpath) method to locate the `pv_name` nodes but you must still decide which to edit.  The macros (with definitions unique to this file) are defined elsewhere in the file.

Describe for us what you plan to do (create a new .bob file from an empty file or edit an existing file that you provide us) and it will be simpler to provide you with an example using lxml.

Regards,
   Pete

On 11/15/2022 8:48 PM, 吴煊 via Tech-talk wrote:

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System