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
Unread November 8th, 2019, 06:29 AM   #1
anirudhgk7
Member
India

anirudhgk7 is offline
 
Join Date: Feb 2019
Location: Kerala
Posts: 35
Allen Bradley 1769-L18ER-BB1B local 1734 point IO modules arrangements

Hello,
I want to connect 1769 L18ER PLC with 8 number of 1734 pont IOs.
24V Dc 8 Channel Sink Input
Module: 3 nos
24V Dc8 Channel Source Output
Module: 2 nos
24V Dc 8 Channel High Density
Analog Current Input Module: 2 nos
24V Dc 4 Points Analog Current
Output Module: 1 nos
We can connect these 8 module directly to the PLC or need extra 24v Dc power (1734-EP24DC) inbetween the module and PLC
  Reply With Quote
Unread November 8th, 2019, 08:33 AM   #2
EastSideSquirrel
Member
Cambodia

EastSideSquirrel is offline
 
Join Date: Aug 2019
Location: Canada
Posts: 9
Quote:
Originally Posted by anirudhgk7 View Post
Hello,
I want to connect 1769 L18ER PLC with 8 number of 1734 pont IOs.
24V Dc 8 Channel Sink Input
Module: 3 nos
24V Dc8 Channel Source Output
Module: 2 nos
24V Dc 8 Channel High Density
Analog Current Input Module: 2 nos
24V Dc 4 Points Analog Current
Output Module: 1 nos
We can connect these 8 module directly to the PLC or need extra 24v Dc power (1734-EP24DC) inbetween the module and PLC
One thing I don't see here, is I believe you need the 1734-AENTR to connect all of your point IO to your 1769-L18ER. When looking at the rockwell datasheet... (https://literature.rockwellautomatio...n040_-en-p.pdf) page 17, it says to "Add up current requirements of modules you want to use to make sure they do not exceed the amperage limit of 0.8 A for the 1734-AENTR or 1734-AENTRK adapter"

Now, I look to the individual product manual of the 1734-IB8.
https://literature.rockwellautomatio...n051_-en-e.pdf
Page 23 will give you the current specs of the module. You do this will all of the modules you want to have as part of your point IO, then insert the ep24dc where the amperage limit of 0.8A is being reached.

I expect someone else to come here and correct or fill in the gaps on this answer.
  Reply With Quote
Unread November 8th, 2019, 08:53 AM   #3
anirudhgk7
Member
India

anirudhgk7 is offline
 
Join Date: Feb 2019
Location: Kerala
Posts: 35
But in 1769 L18 ER PLC can connect 8 expansion IO locally.
  Reply With Quote
Unread November 8th, 2019, 10:14 AM   #4
Geospark
Lifetime Supporting Member
Ireland

Geospark is offline
 
Geospark's Avatar
 
Join Date: Feb 2012
Location: Kildare
Posts: 2,777
Yes, all the 5370 CompactLogix L1 Controllers support a certain number of local expansion I/O module.
So it would not normally be necessary to have to use a 1734 communications adapter to add the first few modules to these controllers.

This is just an example of a 1769-L18ERM with 2 expansion modules added, but up to 8 modules is supported for this controller...



You can use the maximum number of local 1734 POINT I/O modules that the CompactLogix 5370 L1 supports,
provided the total current that the embedded I/O and local expansion modules draw
does not exceed both the available POINTBus backplane current of 1 A (@ 5VDC), and the field power current of 3 A (@ 24VDC).

The backplane current draw, for the available expansion modules, is typically 75 mA @ 5VDC for most standard I/O modules,
but for other modules it can vary anywhere up to 220 mA @ 5 VDC.
Taking a look at your list, which vaguely tells me each type (without catalog numbers)...

Quote:
Originally Posted by anirudhgk7
24V Dc 8 Channel Sink Input Module: 3 nos - 75 mA @ 5VDC each
24V Dc8 Channel Source Output Module: 2 nos - 75 mA @ 5VDC each
24V Dc 8 Channel High Density Analog Current Input Module: 2 nos - 75 mA @ 5VDC each
24V Dc 4 Points Analog Current Output Module: 1 nos - 75 mA @ 5VDC each
...I have added the expected backplane current draw rating for each type you have listed. So, let's total that up...

75 x 3 = 225
75 x 2 = 150
75 x 2 = 150
75 x 1 = 75
Total = 600 mA

As the total backplane current draw that the controller supports is 1 A max. (1000 mA), this tells us that 600 mA is valid, leaving us 400 mA to spare.

As we cannot add any more than the already used 8 expansion modules for this controller, the 400 mA is not further usable.
However, if we were to later swap out a standard 75 mA module for some other speciality module, which draws more backplane current,
then this 400 mA "to spare" could come into play. But if we were to replace too many of the original modules with higher current capacity modules,
then the 1 A current limit could quite possible be exceeded, and an expansion power supply may then be required.

Therefore, it's best if you look up, or know where to look up, the specifications for these POINT I/O modules...

1734-SG001G-EN-P - POINT I/O Modules Selection Guide

Regards,
George
__________________
"A little nonsense now and then is relished by the wisest men".

Last edited by Geospark; November 8th, 2019 at 10:16 AM.
  Reply With Quote
Unread November 8th, 2019, 12:06 PM   #5
anirudhgk7
Member
India

anirudhgk7 is offline
 
Join Date: Feb 2019
Location: Kerala
Posts: 35
Okay thanks you for your valuable reply , then how to calculate field power current.
  Reply With Quote
Unread November 8th, 2019, 12:48 PM   #6
AustralIan
Member
Germany

AustralIan is offline
 
Join Date: Jan 2013
Location: Germany
Posts: 926
Read the Selection guide Geospark sent.
You want the watts dissipated value, and the max current per point and max current per module.
You may be able to fuse some things to bring say your output current down.
Dig ins are
Your digital outputs are max 3A per module, 1A per channel and 2W module dissipation
So...
2W/24V = 0.083A
So each DO module is 3.083A.
If you worked out that each of your digital outputs only draws 20mA, you could fuse them each for maybe 50mA, in which case you would only count 0.483A.
Analog Outs are 21mA per channel and 2.15W module dissipation
2.15W/24V = 0.090A
0.021A*4 = 0.084A
Total per analog Output module is 0.174A.
  Reply With Quote
Unread November 8th, 2019, 01:03 PM   #7
dmargineau
Lifetime Supporting Member
United States

dmargineau is offline
 
dmargineau's Avatar
 
Join Date: Dec 2011
Location: Midwest
Posts: 2,452
The RA Integrated Architecture Builder (IAB) utility does a pretty good job validating architectures and required supply power.

Your particular setup needs a 5A 24VDC power supply which satisfies the PLC and I/O modules' requirements leaving you a 33% 'reserve'.
Attached Images
File Type: gif CmpLogix PointIO Power.gif (245.1 KB, 40 views)
  Reply With Quote
Unread November 8th, 2019, 01:13 PM   #8
AustralIan
Member
Germany

AustralIan is offline
 
Join Date: Jan 2013
Location: Germany
Posts: 926
Quote:
Originally Posted by dmargineau View Post
The RA Integrated Architecture Builder (IAB) utility does a pretty good job validating architectures and required supply power.

Your particular setup needs a 5A 24VDC power supply which satisfies the PLC and I/O modules' requirements leaving you a 33% 'reserve'.
Sometimes.
Not in your example though, as it even says right there in your screenshot "field power status: not supported."
  Reply With Quote
Unread November 8th, 2019, 01:25 PM   #9
AustralIan
Member
Germany

AustralIan is offline
 
Join Date: Jan 2013
Location: Germany
Posts: 926
Also the 3A Geospark quoted for the field power is (according to 1769-td005) shared with the embedded IO of the processor, the outputs having a combined max of 3A.
  Reply With Quote
Unread November 11th, 2019, 08:14 AM   #10
Geospark
Lifetime Supporting Member
Ireland

Geospark is offline
 
Geospark's Avatar
 
Join Date: Feb 2012
Location: Kildare
Posts: 2,777
Quote:
Originally Posted by AustralIan
Also the 3A Geospark quoted for the field power is...shared with the embedded IO of the processor, the outputs having a combined max of 3A.
Yes, and no. I have already mentioned that the field power (FP) current is shared between embedded and local I/O...

Quote:
Originally Posted by Geospark
...provided the total current that the embedded I/O and local expansion modules draw
does not exceed both the available POINTBus backplane current of 1 A (@ 5VDC), and the field power current of 3 A (@ 24VDC).
However, this is "Field Power" to power the "I/O" devices connected to either the embedded or local expansion I/O and not just "output" power. The 3 A rating can include field power connected to both input and output devices. Example - 24 VDC supply (V/C) to a 3-wire inductive sensor where the signal wire is connected to an embedded or local input point. Or, indeed, 24 VDC negative (C) connected to an indicator lamp which is activated from an embedded or local output point. All adding to the consumption of the 3 A FP rating.

Further, the field power FP+ and FP- terminals on the controller are not linked to the VDC+ and VDC- terminals, which supply the processor and POINTBus backplane for the embedded and local expansion I/O. The FP terminals must be supplied separately.

This bit is conditional (or down to the user)...

For the initially released hardware Series A L1 controllers (L16ER, L18ER(M)) we are instructed to use a separate power supply for the controller and field power. In other words, do not wire a single power supply to the VDC terminals and loop to the FP terminals (I'm guilty of it). The reason for this is because the Series A controller's internal power supply was designed as non-isolated. As such, and when the supply terminals have been looped, the controller/backplane would be susceptible to any electrical noise or EMC that might be induced through the field power wiring.

I remember the day I first got my hands on an 5370 L16ER and then went on to read this fascinating design "feature". Two power supplies for a small packaged controller? These comedians never run out of new material, do they? To be honest, I've personally never followed this rule for the few L1's I've installed. But my applications were fairly simple with all discrete I/O devices close by and quite low current consumers. So I'm not advocating ignoring this advice, for everyone. In fact, for some applications it may be preferable to supply the controller and field power separately.

They seemed to have seen some sense though when designing the Series B hardware for the L1 controllers (L16ER, L18ER(M), and newly introduced Series A L19ER). The internal power supply is now isolated from the field power connections which means that we can now connect a single suitable power supply to both the VDC and FP terminals, as there is a greater degree of noise immunity. We can also still choose to wire separate power supplies to these terminals, if we wish.

An important fact to be aware of is that the 3 A rating for the field power is fixed, regardless of the output current made available at the power supply connected to the FP terminals. This is due to the fact that the field power is supplied to the embedded and local I/O V/C terminals through an internal and non-replaceable 3 Amp fuse. So for the field power "calculation", there really is none (or should be none).

As long as you choose a suitably rated power supply to meet or exceed the 3 A field power rating, you should not have to worry about calculating the initial or potentially future current draw. If using a single power supply for the controller/backplane and the field power, then we could take all the guesswork out of this and select a model rating to meet both combined. We know the field power rating is 3 A, so that just leaves the controller...

The power rating for the L1 controller embedded power supply is 30 VA, which is 1.25 A @ 24 VDC. A typical 50 W 2.1 A @ 24 VDC power supply would suit if just connecting the controller power separately, but we are looking to combine this with the field power into a single power supply. So we are roughly looking at say a minimum 5 A rated power supply to power everything. So something like the 1606-XLE120E 120 W 5 A power supply selected in the IAB example would more than suffice.

While not having to use two separate power supplies for the Series B (or A if you choose) L1 controllers, I would still recommend a dedicated power supply just for the controller and field power. All other general 24 VDC consumers for the installation would be best sourced from a separate power supply, typically a 10 A or 20 A model, depending upon application size.

Only if using a power supply of a rating less than the 3 A FP fuse rating would you need to consider calculating the FP I/O current draw. But I would argue, why scrimp here? Just throw the necessary or an overrated power supply at your L1 controllers, and walk away content.

It's also good practice to fuse after the power supply and before the FP terminals with a (from the manual)...

User-provided 4…5 A @ 3.15…5.5 A2t fuse.

Regards,
George
__________________
"A little nonsense now and then is relished by the wisest men".

Last edited by Geospark; November 11th, 2019 at 08:19 AM.
  Reply With Quote
Unread November 11th, 2019, 12:46 PM   #11
AustralIan
Member
Germany

AustralIan is offline
 
Join Date: Jan 2013
Location: Germany
Posts: 926
I do hope the OP paraphrases all the information in this thread for his homework assignment. (Or if not a homework assignment, I hope future students use the entirety for their future homework assignments). Some interesting lessons about not doing the minimum.
  Reply With Quote
Unread November 11th, 2019, 01:51 PM   #12
Geospark
Lifetime Supporting Member
Ireland

Geospark is offline
 
Geospark's Avatar
 
Join Date: Feb 2012
Location: Kildare
Posts: 2,777
Oh, I did forget to add (if there is room!?!)...

One other very valid reason to consider calculating the field power current draw is if you feel it may exceed the 3 A FP fuse limit. Very important. You don't want to, and protection aside, potentially overload the controller FP circuit and blow that 3 A non-replaceable fuse. You can always stick a clamp-on ammeter on the supply wires though to "see how you go" as you add the various suspect loads. If the application requires more than the 3 A rating allows, then it's time to add a dedicated external field power supply and utilize the likes of the aforementioned 1734-EP24DC or even 1734-FPD module (Field Power Distribution).

G.
__________________
"A little nonsense now and then is relished by the wisest men".
  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
Local Allen Bradley Support in Egypt. Elcan LIVE PLC Questions And Answers 20 December 13th, 2015 02:25 PM
Read and Write to Local IO Tags Within a FOR Loop WCD_BWDG LIVE PLC Questions And Answers 23 November 3rd, 2011 08:43 AM
AB 1734-AENT POint IO issue ettikudiappan LIVE PLC Questions And Answers 0 July 17th, 2007 10:42 PM
What is D in PID? ... fundamentals of Derivative Ron Beaufort LIVE PLC Questions And Answers 20 March 2nd, 2005 02:26 AM
Allen Bradley 5/40L with local I/O extension nfvtmeinc LIVE PLC Questions And Answers 2 June 10th, 2003 10:55 PM


All times are GMT -5. The time now is 03:31 PM.


.