Re: lso record

[Michael Davidsaver <mdavidsaver at gmail.com>]

On 9/9/24 11:44, Heinz Junkes via Tech-talk wrote:
> Good evening,
>
> I have a problem with the lso (long string out) record.
>
> When I use it as a replacement for stringout (limited to 41 char),
>
> according to the Record reference Manual : "To initialize a string output record it is simplest to set the VAL field directly"
>
> record(lso, "$(user):zone0")
> {
>      field(VAL, 'blabberblabberblub')
> }
This is expected.  lso/lsi are similar to waveformRecord in that VAL is an array.
Array fields can't be initialized prior to `iocInit()` as this is when memory
for that array is allocated.

As you have already found, the way to handle this (so far) since w/ Base 7.0 is
DOL with a "const" link.


>    field(DOL, {const:"/sys/devices/virtual/thermal/thermal_zone0/temp”})

As for the "Bad Field value" message, I agree that this is a less than helpful
error message.


> I get the following message:
>
>
> dbLoadRecords "db/tempLinuxExample.db", "user=ares"
> Can't set "ares:zone0.VAL" to "blabberblabberblub"  : Bad Field value
> ERROR:  at or before ')' in file "db/tempLinuxExample.db" line 7
>
>   7 |     field(VAL, 'blabberblabberblub')
>
> ERROR failed to load 'db/tempLinuxExample.db’
>
> We then tried the contradictory definitions of the description:
> "DOL can also be a constant instead of a link, in which case VAL is initialized to the constant value.”
>
> record(lso, "$(user):zone0")
> {
>      field(DOL, 'blabberblabberblub')
> }
>
>
> epics@ares:~$ caget -s ares:zone0.VAL$
> ares:zone0.VAL$ 41 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
>
> But I don't quite understand this:
>
> "The first field that determines where the desired output originates is the output mode select (OMSL) field, which can have two possible values: closed_loop or supervisory. If closed_loop is specified, the VAL field's value is fetched from the address specified in the Desired Output Link field (DOL) which can be either a database link or a channel access link. If supervisory is specified, DOL is ignored, “
>
> record(lso, "$(user):zone0")
> {
>      field(OMSL, "closed_loop")
>      field(DOL, 'blabberblabberblub')
> }
>
> The same output :
>
> epics@ares:~$ caget -s ares:zone0.VAL$
> ares:zone0.VAL$ 41 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
>
>
>
> Danke Heinz