How to use BTR and BTW instruction

[m_ahmad]

How to use BTR and BTW instruction

 

[Eric Nelson]

I assume this is a QUESTION?...

In RSLogix, pulldown menu 'Help', then select 'SLC Instruction Help'. Click on BTR or BTW for a good explanation.

Even better, download the manuals Ron provided links for in THIS POST... :nodi:

If you need more help than that, ask a more specific question.

beerchug

-Eric

 

[Ron Beaufort]

if you’re just looking for “what the heck is it?” type information, then this link might help:

the Block Transfer “mailman” lesson

if you need anything beyond that, then Eric is right ... you need to tell us:

(1) what type processor you’re using (example: PLC-5/20, SLC-5/04, etc.) ...

(2) what hardware you’re trying to communicate with (example: 1771-IFE, PanelView 1000, etc.) ...

(3) if you’re trying to interpret an existing program, then post an example of one of the block transfers (complete with address entries, etc.) and we’ll try to help you understand what function it performs in your program ...

but in a nutshell:

the word TRANSFER means to move information from one location to another ...

the word BLOCK means that the information being moved is all together in one continuous range of locations ...

the word READ or WRITE tells us in which direction (based upon the processor’s point of view) the transfer is moving ...

in other words, if it’s a block transfer READ, then the processor is “reading” the information INWARD TO the processor’s memory FROM some other device ...

but, if it’s a block transfer WRITE, then the processor is “writing” the information OUTWARD FROM the processor’s memory TO some other device ...

from the “common example of usage” department: the 1771-IFE analog input module used with the PLC-5 system REQUIRES that its “configuration” (start up) data be transferred from the processor to the IFE module by a Block Transfer Write ... it also REQUIRES that the analog signal data be transferred to the processor from the IFE module by a Block Transfer Read ...

from the “common mistake” department: a block transfer write does NOT “write” the information ... a block transfer read does NOT “read” the information ... all the block transfer does is MOVE the information ... either OUT OF the processor (if it’s a BTW) – or INTO the processor (if it’s a BTR) ...

hope this helps ... let us know if you need more ...