RE: EPICS Ethernet/IP & ControlLogix

["Hammonds, John P." <jphammonds@anl.gov>]

Oops, I meant to include tech talk on this one 

John Hammonds
Data Acquisition Systems Manager
Intense Pulsed Neutron Source
JPHammonds@anl.gov
(630)252-5317


> -----Original Message-----
> From: Hammonds, John P.
> Sent: Wednesday, August 25, 2004 12:12 PM
> To: 'Kay-Uwe Kasemir'
> Subject: RE: EPICS Ethernet/IP & ControlLogix
> 
> OK here is my setup,
> 
> I have a tag RoughPumpSw that has the following properties in the Edit
Tag
> Pane:
> 
> Tag Name:   RoughPumpSw
> Alias:      Local:2:O.Data.3
> Base Tag:   Local:2:O.Data.3
> Type:       BOOL
> Style:      Binary
> 
> I have a bo record RoughPumpSw that is defined so that
> SCAN:   Passive
> DTYP:   EtherIP
> OUT:    @plc1 RoughPumpSw S 1
> ONAM    ON
> ZNAM    OFF
> 
> 
> It seems that we can start off with the value of RoughPumpSw as 0 on
the
> PLC and I can successfully change it to 1 and the output module on the
PLC
> actually switches on.  When I go to turn it off(0), the value goes
back
> flips back to 1 fairly quickly.  As Kay suggested, I turned on PRO and
get
> back:
> 
> iochammonds> process:   RoughPumpSw
>    link_text  : 'plc1 RoughPumpSw S 10'
>    PLC_name   : 'plc1'
>    string_tag : 'RoughPumpSw', element 0
>    mask       : 0x00000001    spec. opts.: 2
>    plc        : 0x00704DE4    tag        : 0x007FF1F0
> 'RoughPumpSw': write 0
> 'RoughPumpSw': written
> 'RoughPumpSw': got 1 from driver
> 'RoughPumpSw': updated record to tag, val = 1
> process:   RoughPumpSw
>    link_text  : 'plc1 RoughPumpSw S 10'
>    PLC_name   : 'plc1'
>    string_tag : 'RoughPumpSw', element 0
>    mask       : 0x00000001    spec. opts.: 2
>    plc        : 0x00704DE4    tag        : 0x007FF1F0
> 
> 
> This seems to say that the value is read back as a 1 from the PLC
before
> the 0 gets set.  This is a very simple PLC app so I do not see how
delays
> are possible in the PLC.  The ladder logic only has a few simple rungs
and
> a dozen or so tags.
> 
> We have watched the value of RoughPumpSw on the PLC with RSLogix 5000
and
> see no changes.
> 
> If I switch the output field of the bo record to "@plc1
Local:2:O.Data[3]
> all works as expected and I can turn things on and off at will from
the
> IOC.
> 
> I have also tried swithing the OUT of the bo to "@plc1 Relay S 1"
where
> Relay is a Base tag not pointing to anything else.  Here I see the
same
> result where I can set the value to 1 from the IOC but cannot set it
back
> to 0.
> 
> 
> John
> 
> John Hammonds
> Data Acquisition Systems Manager
> Intense Pulsed Neutron Source
> JPHammonds@anl.gov
> (630)252-5317
> 
> > -----Original Message-----
> > From: Kay-Uwe Kasemir [mailto:kasemirk@ornl.gov]
> > Sent: Wednesday, August 25, 2004 8:35 AM
> > To: Bob Dalesio
> > Cc: Hammonds, John P.; tech-talk@aps.anl.gov
> > Subject: Re: EPICS Ethernet/IP & ControlLogix
> >
> > Hi:
> >
> > John, you're right about the "controller" tags.
> > You can access a controller tag "fred" by simply
> > using its name, so your basic record configuration is:
> >    DTYP = "EtherIP"
> >    INP (or OUT) = "@plc123 fred"
> >
> > As you noticed, one can drill down through structures
> > and arrays: Local:2:O.Data[3] accesses the structure
> > "Local:2:0", element "Data", array element #4.
> > All the IOC software does is pass the string "Local:2:O.Data[3]"
> > to the controller, which then decodes the struct & array access.
> > I have a suspicion that there might be a way to access tags
> > in programs by using a syntax that e.g. somehow prefixes the
> > tags in the program with the program name.
> > But I have not found that documented, so you'd have to try
> > various ideas yourself: "<program>.<tag>", "<program>:<tag>" etc.
> >
> > I'm unsure about your BO issue.
> > So "Local:2:O.Data[3]" <-> binary output works?
> > A simple "BOOL some_tag" <-> BO should also work.
> >
> > And the setup
> >   "BOOL tag == alias for Local:2:O.Data[3]" <-> BO record
> > that you describe should also work, unless you are experiencing
> > some strange timing.
> > Assume this:
> > BO record, SCAN="Passive", DTYP="EtherIP", OUT="@plcxyz tag S 1"
> > Set the record's TPRO="1".
> > When you write "1" to the record, you should see that the
> > device support deposits "1" in the tag table and after up to 1
second
> > later,
> > the driver wakes up and writes "1" to the PLC.
> > Then, every second, the driver wakes up again and _reads_(!)
> > from the PLC. This is meant to support the idea that Bob describes,
> > where your PLC might have more than just the IOC messing with its
tags.
> > _If_ the driver now finds the tag on the PLC to differ from what it
> > thinks
> > it should be, so in case the driver finds the tag to be 0 on the
PLC,
> > it will process your record and switch it back to 0.
> > In this case, with TPRO set to 1, you should see a message ala "got
....
> > from driver".
> >
> > But in general, the tag <-> alias tag <-> record should work.
> >
> > -Kay
> >
> >
> >
> > On Aug 25, 2004, at 8:59, Bob Dalesio wrote:
> > > Hi JOhn,
> > > The reason it is going back to 1 - is that the driver reads the
output
> > > and reflects that value in the database. This is done as there may
be
> > > a different master for the outputs - like a Allen-BRadley
PanelMate.
> > > For outputs, it is a good idea to have the IOC write to a boolean
that
> > > is a request to drive an output. Make the output momentary by
setting
> > > the HIGH field. Have it write to a soft variable in the PLC. Then
the
> > > PLC can compute any interlock logic necessary to determine if it
is
> > > safe to write the output.
> > > Kay will have to say more about why the output may not be
changing.
> > > Bob
> > >
> > > On Tue, 24 Aug 2004 20:54:21 -0500
> > >  "Hammonds, John P." <jphammonds@anl.gov> wrote:
> > >> We are starting to examine the use of ControlLogix PLCs at IPNS
and I
> > >> am
> > >> looking at Kay's driver for Ethernet/IP.  We now have our first
test
> > >> setup going and we are looking at some of the subtleties with how
to
> > >> access various types of tags.  I am very novice with any PLC so
> please
> > >> forgive my awkward use of terminology.
> > >>
> > >> It appears that the only tags that are accessible to the EPICS
driver
> > >> are ones provided at the controller level ( in RSLogix 5000 App).
Is
> > >> this correct?
> > >>
> > >>
> > >> We have been able to access inputs (ai & bi) OK but have been
having
> > >> some trouble with binary outs.  So far we have avoided arrays
> > >> altogether.  We have a binary out module ( relay out I believe ).
We
> > >> can control an output of this directly using the base tag
> > >> Local:2:O.Data[3] with a binary output record.  However, when we
> > >> create
> > >> another tag which aliases Local:2:O.Data[3] and point the record
at
> > >> this, we can turn the output on but cannot turn it off. I have an
> > >> EPICS
> > >> screen that allows me to change the value and monitor the RVAL
field.
> > >> Here I see the new value (0) temporarily reflected in the RVAL
&VAL
> > >> fields but then it goes back to 1.  No change is seen in RSLogix
> 5000.
> > >> We can reset the Value with RSLogix 5000 and repeat the process.
The
> > >> same effect is seen for any "soft" tag.  BTW the soft records
that I
> > >> have are type BOOL.
> > >>
> > >>
> > >> Any ideas?
> > >>
> > >>
> > >>
> > >> John Hammonds
> > >> Data Acquisition Systems Manager
> > >>
> > >> Intense Pulsed Neutron Source
> > >>
> > >> JPHammonds@anl.gov
> > >>
> > >> (630)252-5317
> > >>
> > >>
> > >
> > > Bob Dalesio
> > > ldalesio@lanl.gov
> > > 410 557 0297 Maryland
> > > 505 699 1632 Cell Phone
> > >
> >
> >
> >