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Old August 10th, 2018, 07:24 AM   #1
backendcode
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Produced/Consumed tag and CIP connection

Hello Experts,

I would like to ask a general question and just wondering if someone can help me to explain it.

So I have a AB Compact logix processor on my main control panel and I am talking with another AB PLC installed in CNC machine.

I have 1 DINT produced and consumed tag between two PLC and using each bit of my DINT.

My question is, will I use 32 CIP connection if I use all bits of my DINT? or 1 CIP connection for per tag (SINT, DINT, BOOL)

how about if I use 1 DINT of an array with 32 elements which will give me 32 X 32 = 1024 bits to transfer the data and just wondering how many CIP connection I will use in that situation.

Will I use 1 CIP connection for each elements (32 bits) or 32 connection for each elements of my produced/consumed array.

Thank you in advance for the help,

TGIF
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Last edited by backendcode; August 10th, 2018 at 07:26 AM.
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Old August 10th, 2018, 08:34 AM   #2
JasonTheSparky
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Produced and Consumed tags

Starting on page 12 Rockwell lays out the amount of connections used for producing and consuming tags. The bottom of page 14 describes data types. Standard P/C tags are limited to 500 bytes. Safety P/C tags are limited to 128 bytes.
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Old August 10th, 2018, 08:54 AM   #3
backendcode
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Quote:
Originally Posted by JasonTheSparky View Post
Produced and Consumed tags

Starting on page 12 Rockwell lays out the amount of connections used for producing and consuming tags. The bottom of page 14 describes data types. Standard P/C tags are limited to 500 bytes. Safety P/C tags are limited to 128 bytes.
Thank you Jason for the AB manual link,

So I am limited to use SINT datatype with maximum 3 elements of an array to fall under the 500 bytes range


On my concern related to CIP connection, according to manual CIP connection is based on per tag regardless of datatype and how many elements of an array we are using for particular tag

So I will be a good idea to use SINT datatype with maximum 3 elements of an array because I will be using same number of connection if I use one DINT tag but in DINT case I will have less bits as compared to SINT with an array of 3 elements

I hope I get it right,

Thank you again for the help, Much appreciated
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Last edited by backendcode; August 10th, 2018 at 09:05 AM.
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Old August 10th, 2018, 09:22 AM   #4
JasonTheSparky
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Quote:
Originally Posted by backendcode View Post
Thank you Jason for the AB manual link,

So I am limited to use SINT datatype with maximum 3 elements of an array to fall under the 500 bytes range


On my concern related to CIP connection, according to manual CIP connection is based on per tag regardless of datatype and how many elements of an array we are using for particular tag

So I will be a good idea to use SINT datatype with maximum 3 elements of an array because I will be using same number of connection if I use one DINT tag but in DINT case I will have less bits as compared to SINT with an array of 3 elements

I hope I get it right,

Thank you again for the help, Much appreciated
According to the manual, the SINT data type cannot be used. Your data type will have to be DINT, REAL, an array of DINTs or REALs or a User Defined.

Correct me if I am wrong, but it sounds like you may have a misunderstanding of the difference between Bits and Bytes. 1 Byte = 8 Bits. 1 DINT (32 Bits) = 4 Bytes. Your size is limited to 500 Bytes for a standard Produced/Consumed tag, 128 if it is a safety tag.

If you have a lot of data to share between processors, and you are sharing that data with a lot of other devices then it would be a good use of your available connections to condense your data into as few DINTS as possible (Less network traffic, latency yadda yadda)

Not sure how many other connections you are utilizing with your CompactLogix, but according to this CompactLogix manual (page 77) 100 are supported.

Hope some of this info helps!

Last edited by JasonTheSparky; August 10th, 2018 at 09:28 AM.
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Old August 10th, 2018, 09:25 AM   #5
backendcode
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Quote:
Originally Posted by JasonTheSparky View Post
According to the manual, the SINT data type cannot be used. Your data type will have to be DINT, REAL, an array of DINTs or REALs or a User Defined.

Correct me if I am wrong, but it sounds like you may have a misunderstanding of the difference between Bits and Bytes. 1 Byte = 8 Bits. 1 DINT = 4 Bytes. Your size is limited to 500 Bytes for a Produced/Consumed standard tag.

If you have a lot of data to share between processors, and you are sharing that data with a lot of other devices then it would be a good use of your available connections to condense your data into as few DINTS as possible (Less network traffic, latency yadda yadda)

Not sure how many other connections you are utilizing with your CompactLogix, but according to this CompactLogix manual you are allotted 100.

Hope some of this info helps!
You are correct! My bad I get confused with bytes and bits lol but yes you are right!

Thank you for suggestion and correcting me
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Old August 10th, 2018, 09:32 AM   #6
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Happy to help! God knows I've gotten a lot of help from this site myself!
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Old August 10th, 2018, 09:47 AM   #7
Ken Roach
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If you're doing a Produced/Consumed connection, make it bigger than one DINT. The amount of memory and CPU power required to move one DINT or an array of 20 DINTs is very similar, so it's safe to plan for expansion later.

I've often heard the question "why can't I Produced/Consume just one bit ?".

It's technically feasible but the ControlLogix doesn't let you do it so the users don't produce a bunch of one-bit tags and run out of CIP connections.

In your case, you should Produce a DINT or an array of DINTs, and it will use just one CIP Connection.
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Old August 10th, 2018, 09:58 AM   #8
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+1 for a lot of help from this site. I don't know how many times I've been in the field (or the office) and googled a problem, went to the site and gotten an answer that got me going. Great site!!
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Old August 10th, 2018, 01:24 PM   #9
Ron Brown
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Originally Posted by saultgeorge View Post
+1 for a lot of help from this site. I don't know how many times I've been in the field (or the office) and googled a problem, went to the site and gotten an answer that got me going. Great site!!
I must agree with this. I have gotten a number of an answers to questions just be searching the forum.
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Old August 10th, 2018, 06:44 PM   #10
backendcode
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Quote:
Originally Posted by Ken Roach View Post
If you're doing a Produced/Consumed connection, make it bigger than one DINT. The amount of memory and CPU power required to move one DINT or an array of 20 DINTs is very similar, so it's safe to plan for expansion later.

I've often heard the question "why can't I Produced/Consume just one bit ?".

It's technically feasible but the ControlLogix doesn't let you do it so the users don't produce a bunch of one-bit tags and run out of CIP connections.

In your case, you should Produce a DINT or an array of DINTs, and it will use just one CIP Connection.
Thank you Ken, I was more concerned about CIP connection because the controller we have right now is almost running out of CIP connection and sometimes we can't get online to the controller so we need to take out the ethernet cable from HMI to free some connection but we are coming up with an idea of using an array for Produced/consumed tag rather than 5 dint which will free some CIP connections.

Thank you and everyone for the help

Definitely, I agree with everyone, this forum is like big support to everyone doesn't matter how new or how old you are in automation industry and let's not forget the quick response of all the people. You put a question or start your thread within 30 mins you will get an answer or people will start helping.

Thank you again everyone!
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