You are not registered yet. Please click here to register!


 
 
plc storereviewsdownloads
This board is for PLC Related Q&A ONLY. Please DON'T use it for advertising, etc.
 
Try our online PLC Simulator- FREE.  Click here now to try it.

---------->>>>>Get FREE PLC Programming Tips

New Here? Please read this important info!!!


Go Back   PLCS.net - Interactive Q & A > PLCS.net - Interactive Q & A > LIVE PLC Questions And Answers

PLC training tools sale

Reply
 
Thread Tools Display Modes
Old July 6th, 2018, 03:34 PM   #1
AggieRalph
Member
United States

AggieRalph is offline
 
Join Date: Jul 2018
Location: Georgetown
Posts: 1
Question Logix 5000 CIP message Where is Destination element Stored

AB Logix 5000 Controllers
Compact Logix L24ER PLCs
Can not use Produced / Consumed (due to network / bandwidth limitations) so this is not an option

I have setup communication using msg files. I would like to simplfy the process I have by setting up the message block to update like in this document However instead of communicating with multiple controllers I want to communicate with single controller and just change the Source and Destination element dynamically in the program. Currently I am accomplishing what I need by just having multiple message instructions, but I could reduce the number of these just by editing a couple msg blocks dynamically at runtime.

The problem For example on a CIP data table read the Remote Element is located in the Message tag as a text the path is also listed as a txt I can see how to adjust the Remote element dynamically, but how do I adjust the destination element dynamically. Changing the destination element doesn't even appear to change anything within the Message tag so where does it store this?
  Reply With Quote
Old July 6th, 2018, 04:33 PM   #2
Ken Roach
Lifetime Supporting Member + Moderator
United States

Ken Roach is offline
 
Ken Roach's Avatar
 
Join Date: Apr 2002
Location: Seattle, WA
Posts: 14,103
Welcome to the PLCTalk forum community !

The ControlLogix operating system does not allow you to programmatically modify the destination tag reference.

I'll speculate on a handful of reasons. In general, you don't find the ability for a program to "edit itself" in the Rockwell world. Changing the argument for an instruction is pretty close.

Tag arguments for instructions are reduced to a reference to a 32 bit memory identifier when the instruction is compiled; instead of the destination being "Read_Data_Dest[0]" it becomes "@0x4536". The integrity of that Tag Database is a critical part of the Logix OS, and software that seeks to modify it has to jump through the security hoops.

Also, if a MSG were already dispatched into the OS buffers with a memory location to put the result in, they'd have to work out a way to lock the instruction from being modified until that instance completed.

And the number of users who would use such a capability to save on the number of MSG instructions they had to type out would be dwarfed by the angry troubleshooters trying to figure out why the cross reference feature can't find the MSG instruction that's changing the tag they expect.

In my opinion if you are dealing with a network with latency or reliability limitations, you want to keep your MSG logic as bone-simple as possible, even at the cost of some brute-force data entry and lengthy routines.
  Reply With Quote
Old July 8th, 2018, 11:42 PM   #3
rdrast
Lifetime Supporting Member
United States

rdrast is offline
 
rdrast's Avatar
 
Join Date: Apr 2003
Location: South Carolina Lowcountry
Posts: 5,231
Use a UDT to hold your messages.
Make a member of the UDT an index.
The sending controller sends out a message with the target index, the receiver can check the index and handle it appropriately. You can even use the index to just copy the message into an array of the UDT structure if you like.
__________________
------------------------------------
How to ask questions the SMART Way!

Look First, Ask Second!

  Reply With Quote
Reply
Jump to Live PLC Question and Answer Forum

Bookmarks


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Topics
Thread Thread Starter Forum Replies Last Post
RS Logix 500 - When loading is FactoryTalk Service Platform the same as RS Logix 5000 Rob S. LIVE PLC Questions And Answers 3 March 15th, 2017 08:14 AM
RS Logix 5000 - any benefits of loading off CD or Rockwell Website ? Baker in Virginia LIVE PLC Questions And Answers 2 March 11th, 2017 08:52 AM
Ultra 5000 firmware and Logix 5000 69FIREBIRD LIVE PLC Questions And Answers 1 June 26th, 2008 01:48 AM
Howto read serial number of CLX 1756-L61? oldnewbee LIVE PLC Questions And Answers 9 June 18th, 2008 08:46 AM
Ton Timer ICAPALDO LIVE PLC Questions And Answers 41 December 21st, 2004 04:43 PM


All times are GMT -5. The time now is 12:04 AM.


.