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 December 29th, 2017, 06:20 AM   #1
andyhart21
Member
United Kingdom

andyhart21 is offline
 
Join Date: Dec 2017
Location: Chesterfield
Posts: 3
Siemens S7-300 I/O addressing question

Good afternoon, I am hoping someone out there can help me with a query I have about Siemens S7-300 I/O addressing.

We have an S7-400 PLC system with 17 x S7-300 remote I/O racks distributed around the plant. A need has arisen to add another 16 channels of DI to an existing I/O rack. If I do not have enough physical space (it is very tight) to add another 16ch DI at the end of the rack, my thoughts were to replace one of the existing 16ch DI's with a 32ch DI.
My question is, how will Step 7 allocate addresses to this 32ch DI? Will the first 16 channels be automatically addressed to the same as the old 16ch DI, and the second 16 channels be allocated new addresses? I hope this is the case as the existing code obviously uses the original 16 channels.

Also, what is the limit for adding I/O to a rack? Is it just a case of connecting a new module (if this is the way I go) with a bus connector and configuring it in the hardware configurator? I have never changed a module for a different type or added new I/O before so this is new ground for me, I have only ever changed like-for-like. The configuration on this rack at present is as follows:

PS307 PSU
SIMATIC ET200M / LINK
SIMATIC ET200M / LINK
SM321 16ch DI
SM322 16ch DO
SM322 16ch DO
SM331 8ch AI 4-20mA HART

Thanks in advance

Andy
  Reply With Quote
Old December 29th, 2017, 06:45 AM   #2
Pete.S.
Member
United States

Pete.S. is offline
 
Join Date: Mar 2016
Location: Fl
Posts: 457
You can set the address to what you want but I'm pretty sure it has to be consecutive addresses within the module. In other words, you won't get the same address as the original module.

If you want to check it out, just open the project offline and then go to hardware configuration and remove the old and insert the new one and you'll see what options you'll be presented with.
  Reply With Quote
Old December 30th, 2017, 03:47 AM   #3
andyhart21
Member
United Kingdom

andyhart21 is offline
 
Join Date: Dec 2017
Location: Chesterfield
Posts: 3
Thanks for the reply. Sounds like an additional 16ch DI module is the way I should go if possible then. The problem is I cannot do any live testing on the system as it is always in use and I do not have any spare hardware to play with. This is having to be planned in 6+ months ahead to coincide with an outage period at the plant, and will have to go through a rigorous management of change procedure, so I am just trying to get as much information as possible beforehand.

Cheers
  Reply With Quote
Old December 30th, 2017, 04:29 AM   #4
L D[AR2,P#0.0]
Lifetime Supporting Member
United Kingdom

L D[AR2,P#0.0] is offline
 
Join Date: Nov 2006
Location: UK
Posts: 5,531
It all depends on the addresses set for the other digital inputs modules. If there is a gap in the addressing then a 32 input card could have the same base address.
Attached Images
File Type: jpg gaps.jpg (47.8 KB, 65 views)
  Reply With Quote
Old December 31st, 2017, 05:25 AM   #5
Ih8Siemens
Lifetime Supporting Member
United States

Ih8Siemens is offline
 
Join Date: Dec 2017
Location: NoDak
Posts: 46
I think your best course of action would be to find an appropriate trash recepticale, and place the S7 in there and go Allen Bradley :P. I gotta start diversifying and looking into these guys more.
  Reply With Quote
Old December 31st, 2017, 08:30 AM   #6
JBA-DK
Member
Denmark

JBA-DK is offline
 
Join Date: Sep 2015
Location: Haderslev
Posts: 51
It should not be a problem to replace this module. There should not be any problem in using the same addresses and adding 16 more addresses. Just be aware you have an up to date copy of the code. I would take an upload before making any changes. The plc has to go into stop when you download another hardware config to the plc. You can replace an older hardware with a newer hardware but not the other way around without a hardware change and download.
  Reply With Quote
Old January 1st, 2018, 05:39 AM   #7
JesperMP
Lifetime Supporting Member + Moderator
Denmark

JesperMP is offline
 
JesperMP's Avatar
 
Join Date: Feb 2003
Location: Copenhagen.
Posts: 13,241
You have a PS307 PSU as the 1st module in the rack.
You can save one slot by moving this module to another position. It does not have to sit in the same rack as the other S7-300 modules.
In this way you dont have to add a 32-channel module and change wires or make program changes to the existing parts of the program.
__________________
Jesper
3 strikes and you're out
  Reply With Quote
Old January 1st, 2018, 06:02 AM   #8
JesperMP
Lifetime Supporting Member + Moderator
Denmark

JesperMP is offline
 
JesperMP's Avatar
 
Join Date: Feb 2003
Location: Copenhagen.
Posts: 13,241
What is the "SIMATIC ET200M / LINK" ?
And why are there 2 per rack ?

Are they really IM Send-receive expansion modules for S7-300 racks ?
Or are they IM modules for profibus or profinet ?
If so, why are there 2, since there can only be 1 per "normal" profibus/profinet rack ?
Or is that actually a hardware-redundant rack with the special backplane modules which supports 2 IMs per rack ? The i/o does not look like a redundant setup.

Too many questions !!
Post an exact list of type numbers and/or photos please.
__________________
Jesper
3 strikes and you're out
  Reply With Quote
Old January 2nd, 2018, 01:55 AM   #9
andyhart21
Member
United Kingdom

andyhart21 is offline
 
Join Date: Dec 2017
Location: Chesterfield
Posts: 3
Thanks for all the replies guys.

The Simatic Link modules are the IM153 Profibus DP interface modules, and yes there are two for redundancy. I have attached a picture of the system architecture which shows the interface between the CPU's (again redundant) and the remote distributed I/O racks. Note that the remote I/O rack shown in this drawing is not the one in question above.
Attached Images
File Type: jpg Architecture Edit.jpg (52.5 KB, 28 views)
  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
siemens plc s7 300 valski gonzaga LIVE PLC Questions And Answers 25 June 12th, 2013 07:05 PM
Siemens S7 300 PLC and WinCC Flex 2007 HMI peng LIVE PLC Questions And Answers 3 March 17th, 2011 03:13 AM
Explaining how Siemens S7 PLC Addressing Works & Programming Challenges johnwoz LIVE PLC Questions And Answers 4 October 9th, 2008 05:49 PM
S7 300 Move word Question randy741985 LIVE PLC Questions And Answers 15 March 24th, 2008 06:36 AM
Siemens S7 w/ Modicon I/O ??? estover LIVE PLC Questions And Answers 4 December 27th, 2002 12:28 PM


All times are GMT -5. The time now is 04:44 PM.


.