Re: Ethernet/IP Device Support and CompactLogix

[Carl Cork <cwcork@lbl.gov>]

According to CIP Protocol Ed. 2.2 (Dec 2005), C-5.2.6 String Encodings:

a SHORT_STRING consists of a 1-Byte character count followed by count
characters (1 byte per character). Therefore, the Product Name attribute
field should have a maximum length of 33 bytes.

John Dobbins wrote:
> Kay,
>
> Actually, it looks like there may be another interpretation. The product 
> name is defined as (DeviceNet?) type SHORT_STRING. I don't know where 
> this is defined but it looks like it may be: "a single byte length field 
> and 'n' data bytes".
>
> In which case the Product Name is being returned inside a longer field. 
> The Product Name is less than 32 characters but the data field it is 
> returned in is longer than 32 bytes.
>
> EIP_check_interface() rejects the product name because is finds the 
> length of the data returned >32, even though the string length is less 
> than 32.
>
> John
>
> Kay-Uwe Kasemir wrote:
> > On Apr 6, 2006, at 10:22 , John Dobbins wrote:
> > > I just found in Volume I : CIP Common Specification, Release 1.0, 
> > > page 5-10
> > >
> > > "Product Name:
> > > This text string should represent a short description of the 
> > > product/product family represented by the product code in attribute 
> > > 3. The same product code may have a variety of product name strings. 
> > > The maximum number of characters in this string is 32."
> >
> > Excellent, so now you can sue the makers of ControlLogix for violating 
> > the spec ;-)
> >
> > How _did_ you get a copy of the updated specs?
> >
> > -Kay

--
Carl Cork                                 E-Mail:  CWCork@lbl.gov
Lawrence Berkeley National Lab               TEL: +1 510 486 4295
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