Experimental Physics and
Industrial Control System

Dear Madam/Sir,

I am writing here because I would like to suggest an update to documentation as the behavior I observed seems to match the code. It is just not expected (at least it was so for me). Feel free to reject the suggestion if I am misinterpreting anything.

EPICS 7.0.6.1

If conditions are right, dbGetLink() retrieving DBR_STRING from a DBF_ENUM CA link pointing at a PV hosted by a remote IOC may return -1 even though dbIsLinkConnected() says the link is connected. This occurs when dbGetLink() is used with the link for the first time after IOC startup. I assume this is a result of a delayed string monitoring request (CA_MONITOR_STRING) in dbCaGetLink() (dbCa.c). A retry slightly later works as expected. 

Using google I found following documents:

* https://controlssoftware.sns.ornl.gov/training/2019_USPAS/Presentations/02b%20AppDevGuide_3_15_6.pdf

* https://epics.anl.gov/base/R3-14/12-docs/AppDevGuide/node16.html#SECTION001642000000000000000

Yet, none of them seems to mention this behavior next to the description of dbGetField(). Also, dbCa.h does not describe it. And, I was not able to find description of dbGetLink() at https://epics-controls.org/. Yet, I admit I gave up after I got lost there. Still, unless my explananation is incorrect, would it possible to add description of this behavior to documentation of dbGetLink() unless it is already there, please? Something like this:

Thank you.

Sincerely,

Ivo Hanak