Byte order of Modbus CRC

  • Thread starter Steve Ciricillo
  • Start date
> Speaking in an official capacity, I should point out that the PI-MBUS_300.PDF ("original" from 1996) is obsolete. The "Modbus Serial Line Implementation Guide v1.0 November 2002" is the current document you should be using. PI-MBUS_300.PDF is only on www.modbus.org because so many people kept asking for it to look up legacy issues. <

May I suggest that the PI-MBUS_300.pdf document be emblazoned with "OBSOLETE" on it so we know that should not be used anymore!

Also, in addition to the "Modbus Serial Line Implementation Guide v1.0 November 2002", the other document you'll need is "MODBUS Application Protocol Specification V1.1", which describes the protocol itself.

Regards,

tom
 
S

Steve Ciricillo

> May I suggest that the PI-MBUS_300.pdf document be emblazoned with "OBSOLETE" on it so we know that should not be used anymore!
>
> Also, in addition to the "Modbus Serial Line Implementation Guide v1.0 November 2002", the other document you'll need is "MODBUS Application Protocol Specification V1.1", which describes the protocol itself. <

Interesting how the Schneider Electric site (which comes up when you type www.modicon.com)states the following in response to a FAQ:

Q: "Where can I get general information on Modbus?"
A: "Part number PI-MBUS-300 references the Modbus Protocol Reference Guide. It can be found on this web site. From the main menu, select Support/Services, Modbus, Modbus Technical Manuals, PI-MBUS-300 Modbus Protocol Reference Guide or search for PIMBUS300."

What's even more interesting is that there is no Modbus link under the Support Services menu, so this site is definitely giving misleading info.

The place to go is www.modbus.org. Click "Modbus Standard Library" and click Accept to the legal agreement. Then all of the above mentioned files are available for download.

Regards,
Steve C.
 
In case you didn't know it, Modbus.Org (www.modbus.org) is a new organization only recently formed with Ken Crater (the founder of the Alist) as the Managing Director. He only assumed the task of leadership a few months ago. It will take serious time for Ken to get all of the documents previously supported only by Schneider Electric into his servers. Give the guy a break! Modbus.Org is now an independent organization to support the Modbus specification and the use of the Modbus logo and trademarks. This gives Modbus the same standing as Foundation Fieldbus, ODVA, Profibus, and ControlNet - among many others.

Dick Caro
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S

Steve Ciricillo

> In case you didn't know it, Modbus.Org (www.modbus.org) is a new organization only recently formed with Ken Crater (the founder of the Alist) as the Managing Director... Give the guy a break!
>

Sorry, but perhaps I was misunderstood.

My negative comments were in regards to the Schneider Electric site, NOT against Modbus.org. Modbus.org IS the place to go and Ken has done a great job. It is there that the correct and up to date documents can be found. I was just trying to clarify this for the benefit of others posting to this thread. I'm glad to see Modbus getting the official attention and recognition it deserves. Its popularity speeks volumes!

Regards,
Steve C.
 
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