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Subject: Re: Ethernet/IP Device Support and CompactLogix
From: Kay-Uwe Kasemir <[email protected]>
To: John Dobbins <[email protected]>
Cc: EPICS Tech-Talk <[email protected]>, John Barley <[email protected]>
Date: Wed, 05 Apr 2006 15:40:56 -0400
Hello:

On Apr 5, 2006, at 14:59 , John Dobbins wrote:
I have just used the EPICS Ethernet/IP device support to talk to an Allen Bradley CompactLogix (i.e. not ControlLogix) module.

So far I have written a bit to a DINT and read a PLC boolean. The only trouble encountered was an error/warning message on start-up:

    drvEtherIP: launch scan task for PLC 'compactlogixtest'
    EIP_startup: cannot determine target's identity

Well, unless there's some other error in the code that I don't see, this means:
The driver tried several "GetAttributeSingle" calls on the "Identity Object"
of the device, and that failed.
Specifically, it's trying to read the Vendor ID, Device Type, Revision, Serial # and Product Name,
which are all "Attributes" of that "Identity" object.
That was about the first thing I tried when implementing the driver.
I don't really care about the result except for diagnostics purposes,
so the driver will march on even if that fails
- and that seems to work out OK for your test.


But the thing is:
The ControlNET specification that I used when implementing the driver
(Release 2.0 Errata 2) makes no mistake that ".. the Identity Object shall
be present in all devices". And while some of its attributes are optional,
the Vendor ID ... Product Name are "Required" (Part 10a, p.2 & 3 of the specs).
This tells me that CompactLogix isn't fully spec compliant.
Might be OK, who cares about the serial number?
Might be problematic, because what else is different in the CompactLogix
interpretation of the specs?


Before I go any further with this test I wanted to ask if there is any chance of EPICS community support for CompactLogix - OR - should I send back this loaner, tell my colleagues that EPICS only supports ControlLogix, and turn my attention to other tasks?

This test came about because a colleague was interested in CompactLogix as it appeared to have lower capital costs. I gave them the spiel about EPICS device support only being demonstrated to work with ControlLogix but said if they could get a loaner I would give it a try.
Well, the beauty of the community is that several other people might be very interested in CompactLogix
and work with you on this.
As for me, I developed that driver because I originally needed it for my SNS-related work.
I still maintain it as far as bug fixes and adaptation to new EPICS releases are
concerned, and I would gladly attempt to incorporate any modifications that
allow its use with CompactLogix.
But since I'm not using CompactLogix, actually have not been using ControlLogix
in any of the subsystems assigned to me for years, it is very unlikely that I
can provide more active support for a CompactLogix adaptation.


-Kay


Replies:
Re: Ethernet/IP Device Support and CompactLogix John Dobbins
References:
Ethernet/IP Device Support and CompactLogix John Dobbins

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