Experimental Physics and
Industrial Control System

Script works as expected with mbbi record:

  7 import epics
  8 import time
  9
 10
 11 pv_name = 'INVALID_PV_NAME'
 12
 13 def pv_with_callback(pv_name):
 14     pv = epics.PV(pv_name)
 15     time.sleep(2)
 16     def on_value_changed(char_value, **kws):
 17         print("Char Value: ", char_value)
 18     pv.add_callback(on_value_changed)
 19
 20
 21 pv_with_callback(pv_name)
 22
 23 time.sleep(2)
 24 pv_name = 'status'
 25
 26 pv_with_callback(pv_name)

Thanks,
Tong

On 2/18/19 5:49 PM, Matthew Newville via Tech-talk wrote:

On Mon, Feb 18, 2019, 4:30 PM Zhang, Tong via Tech-talk <[email protected] <mailto:[email protected]> wrote:

    Hello,

    When I work with PyEpics.PV object, I've found sometimes the value
    of 'char_value' in the added callback just return what 'value' meant
    to be. I tried with a MBBI type record, it should be expected as a
    string in the callback, but an integer was got. Could somebody let
    me know what is the possible reason?

An mbbi record definitely should return the appropriate string in 'char_value' in a callback.  That does need to be able to lookup the CTRL values, especially including the enumeration strings.

Can you do
     mypv = epics.PV(pvname)
     print(mypv.get(as_string=True))
     print(mypv.get_info())

and see the enumeration strings?

Matt

Replies:

Re: Issue of PV callback of PyEpics Tong Zhang via Tech-talk

References:

Issue of PV callback of PyEpics Zhang, Tong via Tech-talk

Re: Issue of PV callback of PyEpics Matthew Newville via Tech-talk

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