Re: Remote I/O

[David Dudley <ddudley@bnl.gov>]

Title: Re: Remote I/O

For NSLS-2, all configuration and logic is planned to be incorporated into the IRMIS system, as a single database layout.

>From that database, we plan on being able to create XML files of the logic for the PLC’s, as well as the appropriate EPICS I/O configuration for that configuration, and therefore restrict all database mapping layouts to a single source, from which we can regenerate all I/O and memory configurations, without having to justify the PLC I/O map to the EPICS I/O map.

In addition, I should have initially mentioned that one of the primary reasons for the A-B choice is that it uses a communications format named ‘CIP’, and its internal memory configuration is entirely driven by TAGNames.

In tne ControlLogix platform, you do not do programming or configuration by having to remember or know things like “... ‘B-703:R-E5<OTB>T-1’  is wired to terminal IW102... (That’s Building 703, Room E5, Optical Testing Lab, Temperature 1)” .

Internally, you define signals (and use them in their entirety) by saying “.... B703:R-E5<OTB>T-1”.  Then, when you’re finished programming and testing, you assign that signal, through an ‘alias’, to the physical I/O location.  In most PLC’s, the I/O location itself is the ‘anchor’, and symbols and labels are not much more than comments.  In the A-B, the Tagname drives everything, and at the end, that is simply assigned to an I/O location.

Now, of course that’s a slight oversimplification.  Tagnames in A-B are allowed 38 chars (which is perfect), but pretty much limited only to alphanumeric.  The  exception are the ‘_’, and a couple of other special chars.  To convert a EPICS name to a A-B (or CIP) form, all I actually have to do is to replace all the special characters in a name (the ‘:’ for example) with an allowed char (like ‘_’).  That converts names like ‘B-703:R-E5<OTB>T-1’ to something like ‘B_703_R_E5_OTB_T_1’, which is less readable, but still understandable.

David


On 12/16/09 5:08 PM, "Matthias Clausen" <Matthias.Clausen@desy.de> wrote:

> Hi Bob,
>
> Dalesio, Leo wrote: 
> >    RE: Remote I/O  
> >
> > This ability to define the PLC code and logic in ASCII was the primary reason identified by David Dudley in our choice for AB over Siemens and Yokogawa. Yokogawa has responded that they plan to add this ability.
> >  
> >
> > Matthias - are you saying that you can do this with the Siemens PLC? Can you define the logic in ASCII as well? 
> >  
> I am sorry - it is not the logic itself but the memory layout of all the nodes on the Profibus (including the memory layout of the PLC) which we configure with a CSS tool. This generates a XML files which gets loaded to the IOC.
> This was possible because we have the driver source code in our hands. Using the Siemens tools you will generate a binary file which will be loaded to the hardware board by some Windows DLLs - so no way to get this running on Linux or vxWorks :-(
>
> Why would you want to cerate an ASCII file of the actual logic? Isn't this loaded via Ethernet to the PLC or burned into EPROM? Or are you loading the code to the PLCs via an IOC?
> >  
> >
> > The cost of keeping the PLC software in synch with the IOC was considered significant. 
> >  
> There's a payload on both sides - the PLC and the IOC.
> You need to map PLC-IO into the memory of the (PLC) communication controller and map another time the memory in the dual ported RAM on the IOC into EPICS record addresses. Both configurations (except the PLC program itself) can be handled with our solution.
>
> Cheers
> Matthias
> >  
> >
> >   
> >  
> >  
> >
> > -----Original Message----- 
> >  From: tech-talk-bounces@aps.anl.gov on behalf of Matthias Clausen 
> >  Sent: Wed 12/16/2009 10:02 AM 
> >  To: Ralph Lange 
> >  Cc: EPICS Tech Talk 
> >  Subject: Re: Remote I/O 
> >    
> >  Hi Ralph, 
> >  
> >
> > Ralph Lange wrote: 
> >  > On Wed 16 Dec 2009 8:16:17 Matthias Clausen wrote: 
> >  >> Hi Nick, 
> >  >> 
> >  >> [...] In our case sensors and actors are directly connected to  
> >  >> Profibus. The remaining I/O is connected through WaGo I/O with a  
> >  >> Profibus controller. Profibus driver and configuration is available  
> >  >> from us - even with redundancy support...  
> >  > 
> >  > Hi Matthias, 
> >  > 
> >  > is that using the 1996 IPAC-Profibus Interface that is listed in the  
> >  > hardware support database on the EPICS web site? 
> >  no - it's a new driver which support the Softing PC 104 cards. Softing  
> >  is now producing also a Compact PCI card for us. 
> >  There's a special firmware available which supports redundant Profibus  
> >  connections and fail-over - in conjunction with the redundant IOC. 
> >  
> >
> > Configuring Profibus (DP - or PA) is quite complicated. You have to map  
> >  memory space of the I/O devices into the DPM on the IOC. So you need to  
> >  configure your records's addresses in a way that they match with the DMP  
> >  layout. 
> >  We have developed a configuration tool in CSS which creates an XML file.  
> >  (Like the Siemens 'Step 7' tool) This file is parsed on the IOC and  
> >  creates the memory layout in the DPM. The EPICS records get their  
> >  Profibus address from a reference in the configuration database. (When  
> >  the db files gets created) 
> >  
> >
> > We should finally write some documentation about it ;-)) 
> >  
> >
> > Thanks 
> >  -Matthias 
> >  > 
> >  > Ralph 
> >  > 
> >  
> >  
> >
> > --  
> >  ------------------------------------------------------------------------ 
> >  Matthias Clausen                         Cryogenic Controls Group(MKS-2) 
> >  phone:  +49-40-8998-3256                Deutsches Elektronen Synchrotron 
> >  fax:   +49-40-8994-3256                                    Notkestr. 85 
> >  e-mail: Matthias.Clausen@desy.de                           22607 Hamburg 
> >  WWW-MKS2.desy.de                                                Germany 
> >  ------------------------------------------------------------------------ 
> >