Quick question: Discrete IO does not need Block Transfer

ckchew666

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Aug 2003
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Hi,

I'm sorry if this question has been asked before, but just want to confirm that the discrete IO does not require Block Transfer, right?

Block transfer from Flex IO to PLC5.

I don't have hardware to figure it out....anyone can throw in some feedback? Thanks.
 
No, Discrete I/O falls within the normal slot addressing range of PLC5 Remote I/O, so it doesn't need block transfer.

Block transfers are needed when you need to transfer more than one machine word from a slot.
 
Block transfers are needed when you need to transfer more than one machine word from a slot.
Just a small correction.
With "1/2-slot" addressing, 2 words are assigned per slot.
So you can access up to 32 digital io per slot without blocktransfers.

Because of the particular addressing scheme with RIO, a degree of planning ahead is a good idea when specifying remote io modules.
For example, mixing many 8 point modules with a few 32 point modules in the same rack will be a waste of address space.
 
Thx for the replies.

BTW, I use one slot addressing with 32 points in Flex IO, provided i arrange them 1 Input, 1 output, 1 input, 1 output. Am i right? So, the ASB can accomodate 4 32 points module.
 
JesperMP said:
Just a small correction.
With "1/2-slot" addressing, 2 words are assigned per slot.
So you can access up to 32 digital io per slot without blocktransfers.

Because of the particular addressing scheme with RIO, a degree of planning ahead is a good idea when specifying remote io modules.
For example, mixing many 8 point modules with a few 32 point modules in the same rack will be a waste of address space.

If I have 2 Flex IO adapter connecting to the PLC 5, can 1 Flex adapter set to 1/2 slot addressing and another set to 1 slot addressing?
 
Yes you can mix and match the addressing modes, but I usually recommend against it just to make troubleshooting easier.

Also, your arrangment of I/O (Input/Output/Input/Output) is exactly what is required for the 32-point and 1/2 slot addressing.

OG
 
Operaghost said:
Yes you can mix and match the addressing modes, but I usually recommend against it just to make troubleshooting easier.

Also, your arrangment of I/O (Input/Output/Input/Output) is exactly what is required for the 32-point and 1/2 slot addressing.

OG

Hi,

Correct me if I'm wrong, I taught (INPUT/OUTPUT/INPUT/OUTPUT) arrangement (32 discrete) is the arrangement for 1 slot addressing?

If we use 1/2 slot addressing we can put (INPUT/INPUT/OUTPUT/OUTPUT)? Yes? No?

Thanks.
 
No. On the 5's, 1 slot addressing allows for one word per slot. That is the most universal, as it allows for a complete mix and match of input and output modules. Remember, the PLC 5 series is based on R/G/S addressing. The 'R' as Rack is obvious. The 'G' part, (group) is less so; the 'S' part is the actual slot in the group (and can be 0 or 1).

I actually typed a lot here, explaining the difference, but frankly, I've forgotten, as I always use one slot mode. The PLC5 offers 1 slot, 1/2 slot, and I believe 2 slot addressing. Looking them up in the manual will define them better than what I was typing (and prevent me from looking like a fool (unless a true AB Guru like Ken, Opera, or Jesper reply )) <smile>
 
I know how you feel rdrast...it all kind of runs together. I almost always use 1-slot, but every once in a while the others pop up.

Here's a little summary:

2-slot
======
8-point any card any where (designed for this method)
16-point must alternate
32-point not allowed

1-slot
======
8-point any card any where (poor use of memory)
16-point any card any where (designed for this method)
32-point must alternate

1/2-slot
========
8-point any card any where (poor use of memory)
16-point any card any where (poor use of memory)
32-point any card any where (designed for this method)

OG
 
Operaghost said:
I know how you feel rdrast...it all kind of runs together. I almost always use 1-slot, but every once in a while the others pop up.

Here's a little summary:

2-slot
======
8-point any card any where (designed for this method)
16-point must alternate
32-point not allowed

1-slot
======
8-point any card any where (poor use of memory)
16-point any card any where (designed for this method)
32-point must alternate

1/2-slot
========
8-point any card any where (poor use of memory)
16-point any card any where (poor use of memory)
32-point any card any where (designed for this method)

OG

OG,

Thx for ur summary :) Now it's clearer.
 
My colleaque just came back from the site (PLC-5 to Flex IO installed).

The told me that the PLC-5 RIO port is linked to the Flex IO as (ASB/IA16/IA16/OA16/OB32/OB32/IB32/IB32) <-- jst ONE ASB

Does this settings means the PLC-5 & Flex IO is using 1/2 slot addressing and the it's divided into two RACK?

1/2 slot, RACK 1 = IA16/IA16/OA16/OB32
1/2 slot, Rack 2 = OB32/IB32/IB32

Pls correct me if I'm wrong, we never play around with 32 pts module before :)

Thanks.
 
JesperMP said:
Yes, it must be configured as 2 racks with 1/2 slot addressing.

Thx for ur confirmation, I do not know it Flex 10 ASB can be configured as 2 rack per ASB :( Too used to 16 pts Flex module with 1 slot addressing :)

Anywhere thx a lot for everyone :)
 

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