Slc 5/04 Block Transfer

The Plc Kid

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The Plc Kid
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I am adding some BTW / BTR instructions to a slc 5/04 processor and i have 2 questions.

1.0 Following the attached example i am trying to determine which of these methods i need to use if any. It willbe bi-directional reads and writes about 14 each.

2.0 I am trying to understand correctly if i should interlock when they trigger and why? These will all need to continious but i have heard that you do not want to fire them all at once.Should i interlock a read and write by the example and then interock this set to my other sets?

How could i accomplish this. I am stuck on how to do this properly.
 
You only need the send the setup at first scan, so configure your writes for first scan only.
Then use the error and done bit for continuous reads.
If not_error and not_done then BTR.
 
Ken Moore said:
You only need the send the setup at first scan, so configure your writes for first scan only.
Then use the error and done bit for continuous reads.
If not_error and not_done then BTR.
Click to expand...

Ken,
From a previous post by the OP, I believe the OP is trying to communicate with a RIO PanelView. Needs to clarify this. In that case doesn't he need to use the BTW also?
 
Mickey said:
Ken,
From a previous post by the OP, I believe the OP is trying to communicate with a RIO PanelView. Needs to clarify this. In that case doesn't he need to use the BTW also?
Click to expand...

It all depends on what you are talking to, and what it requires.

Anytime you need to write configuration data to a device then what Ken has said is true, as it should not lose that data unless the system is powered down, or a module is replaced or faulted. But, if the device needs continuous updates, then you would want to write the block transfers to do that.

I'm not familiar enough with RIO Panelviews, but I would assume the PLC has to push display data to the Panelview? In that case it would constantly need to write.
 
Last edited:
Mickey

You are correct this is in addition to my previous thread here http://www.plctalk.net/qanda/showthread.php?t=49325

I am communicating to a pv 1000 standard over RIO as well as to flex I/O over RIO

I am trying to change from the old style transfer of copies and moves to the BTR / BTW instruction

So i will have reads and writes to the pv as well as to the flex i/o as some are input modules and some are output modules.

I will have 14 reads and 14 writes total 4 of the 14 are for the pv and the rest flex i/o.

My question is do i fire a 7 sets at once? With a btr and a btw interlocked? Or do i sequence through them somehow based on the done bits?

I am sorry for all the questions but i can not seem to find a good example anywhere and even ab tech support could not confirm an answer to these questions.

Please Help :cry:
 
I tried ken roach suggestion from post 14 here http://www.plctalk.net/qanda/showthread.php?t=49325

But that slowed the network down so bad that it would take a full minute for the pv scrren to change when you pressed a button.

I think it would be easier to put all of this on block transfer instructions and control them correctly i have the addresses mapped out i just need help sequencing them the right way.
 
The Plc Kid said:
It willbe bi-directional reads and writes about 14 each.
Click to expand...
If you don't mind me asking - 14 reads and writes? According to my knowledge of A-B block transfers, that's 777 words. Are you actually moving this many words?
 
The scanner should be able to support one block transfer to/from each logical rack per RIO scan.

So, you should be able to only interlock those transfers that are intended for each logical rack to ensure that they all execute.

So, you would interlock the 4 transfers for the panelview, so that only one of them executes at a time.

Then, interlock the pairs for each of the analog cards, and if they're in the same logicl rack, interlock those with each other as well.

Hope this helps
Paul
 
Okie

what is the best way to interlock these? With the dn bit? or a timer? The old transfers in this program used a couter that was incremented by a timer to interlock them but that just does not seem to be the best way to do it.

What is the best interlock method to use?
 
The Plc Kid said:
Okie

what is the best way to interlock these? With the dn bit? or a timer? The old transfers in this program used a couter that was incremented by a timer to interlock them but that just does not seem to be the best way to do it.

What is the best interlock method to use?
Click to expand...

Typically, the EN bits are used to interlock them.

Since there are four of them to the PV, you could keep the timer/counter arrangement and fire one off every 0.25 seconds for example. That would help ensure that they all get triggered.

Then they should all complete every second. If you want faster throughput, cut the timer preset.
 

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