rslogix 500 program knowledge needed

stu

Member
S
Join Date
Aug 2005
Location
England
Posts
779
Hi
I have a machine which has recipes in the plc ,using indirect addressing, we have a screen where we enter the recipes and then save the recipe to a f data base in the plc
, on the recipe save screen we use about 10 valves that save in the recipe - F34:0 -F35:11 We copy the F numbers to a float database via the recipe number so if recipe 50 we are 50 so F100 would copy that data across to a length of 20 (which I think is 20 bits)
If i wanted to have a button info on/off in a recipe could i use a spare F number (f34:13 ) is it possible to do this ??
I hope this makes sense ?
Thanks stu
the is it posible if I use a
 
stu said:
Hi
I have a machine which has recipes in the plc ,using indirect addressing, we have a screen where we enter the recipes and then save the recipe to a f data base in the plc
, on the recipe save screen we use about 10 valves that save in the recipe - F34:0 -F35:11 We copy the F numbers to a float database via the recipe number so if recipe 50 we are 50 so F100 would copy that data across to a length of 20 (which I think is 20 bits)
If i wanted to have a button info on/off in a recipe could i use a spare F number (f34:13 ) is it possible to do this ??
I hope this makes sense ?
Thanks stu
the is it posible if I use a
Click to expand...

Please try again with your question. I'm sure what you want is possible but your post is too garbled to understand....
 
I am with Daba, the problem isnt clear.
If what I am assuming about what you're asking is correct, you would want to use a bianary "B" data type since on/off is 1/0... if you are asking about how you would integrate an on/off bit in a floating point "f" word, then that is possible but it takes some creative thinking but can be done. I would try to re-write what you are trying to achieve and explain it a little better.
 
Sorry guys
, I was trying to brain dump the machine info , and didn’t work very well,
Yeah is it possible to use F data as a binary as b bits 1/0, then I can still use the recipe float spares for a on/off button
 
I would personally avoid manipulating at the bit level. Only because i don't know what will happen. Others might have some insight.

Instead I'd use zero as my off state and say, 10 as my on state. Zero in FP is always zero, but a number like 10 might be stored and evaluated as 9.9999995 or whatever.

So if you evaluate it as "zero" or "greater than Zero" that gives you your binary state.
 
So have a b3:1/0 xic could mov 0 to F34:13
And B3:1/0 xio could move 10 into F34:13

But that wouldn’t be turn the button on in the recipe,would it ?
Could we do an expression b3:1/0 = 1 then F34:13 =10 else b3:1/0= 0
Not to sure on this ?
Thanks for you help guys
 
Stu - you absolutely cannot address the "bits" of a "F" data-file, either read or write.

It looks as though you can enter them as addresses (e.g. F8:0/1), but the compiler rejects them, see the picture....

2018-01-07_105258.jpg
 
stu said:
Sorry guys
, I was trying to brain dump the machine info , and didn’t work very well,
Yeah is it possible to use F data as a binary as b bits 1/0, then I can still use the recipe float spares for a on/off button
Click to expand...

Oh it’s possible, the argument there is then is it safe. I wouldn’t recommend doing that personally.
 
This is an on a machine programmed by The OEM, the only reason I can see is that we are using weight of flour , pail oil ,Rapeseed oil, water and use decimal point 20.5 kg etc
Thanks stu
 
daba said:
Stu - you absolutely cannot address the "bits" of a "F" data-file, either read or write.

It looks as though you can enter them as addresses (e.g. F8:0/1), but the compiler rejects them, see the picture....
Click to expand...

I had to come back an retract my statement after reading your quote... I was thinking B as a word and not F data.
 
Stu, if you really have to use an "F" data-table address as a "binary" flag, you could just use a comparison instruction...

example : use values 0 and 1 in the float data-file to represent "false" (0), and "true" (1).

then in your code "GRT, F8:0, 0.5" would be true for "1" and false for "0".
 

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