Experimental Physics and
Industrial Control System

Mark Rivers <[email protected]> · Tue, 21 Apr 2015 13:03:13 +0000

I believe that if you set the MDEL field of the record to -1 then you will receive a monitor every time the record processes, even if the value has not changed.

Mark

________________________________________
From: [email protected] [[email protected]] on behalf of bohmm [[email protected]]
Sent: Tuesday, April 21, 2015 7:47 AM
To: Tech talk
Subject: EPICS PV updating value

Hello,
  I have the following record in my database:

# Read latest power measurement
#
record(ai, "$(head):ReadPower") {
   field(DESC, "Power")
   field(EGU, "$(egu=J)")
   field(PREC, "4")
   field(DTYP, "stream")
   field(INP, "@gnt.proto get_value($(channel)) $(port)")
   field(SCAN, "I/O Intr")
   field(FLNK, "$(head):ReadPowFan")

}

in the corresponding .proto:

get_value   { in "\$1:%g";  }

The frequency of the external trigger is 0.5 Hz (should expect update
every 2 seconds). However, when I put a camonitor on it (default
camonitor settings):

camonitor HJ-D-P4-EM-2:ReadPower

I sometimes get longer intervals between value updates than 2 second
(multiples, logically), but I need to catch every value of the PV. I
guess it is because the value doesnt change meanwhile:

HJ-D-P4-EM-2:ReadPower         2015-04-21 13:41:21.029564 0.0001036
HJ-D-P4-EM-2:ReadPower         2015-04-21 13:41:23.032038 0.0001267
<----
HJ-D-P4-EM-2:ReadPower         2015-04-21 13:41:27.036535 0.0001497
<----
HJ-D-P4-EM-2:ReadPower         2015-04-21 13:41:29.037671 0.0001152
HJ-D-P4-EM-2:ReadPower         2015-04-21 13:41:33.043594 0.0001036
HJ-D-P4-EM-2:ReadPower         2015-04-21 13:41:35.044982 0.0001382
HJ-D-P4-EM-2:ReadPower         2015-04-21 13:41:37.046880 0.0001152
HJ-D-P4-EM-2:ReadPower         2015-04-21 13:41:39.048397 0.0001267
<----
HJ-D-P4-EM-2:ReadPower         2015-04-21 13:41:43.053185 0.0001152
<----

How do I get the PV value update every time on an external trigger, even
if the value doesnt change.

I apologize for the bad formulation, I am an EPICS newbie.

Thanks

Marek Böhm

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System