Omron PLC Floating Point Divide doesn't work

nightline

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Feb 2010
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Gents,

We had to replace an CJ1G cpu for an CJ2M to get an Ethernet port on a machine.
I uploaded the PLC program including memory area, and changed the CPU type in the software.
I'm using the trail version of the CX-Programmer.
After replacing the CPU, I downloaded the converted program.
But now the machine will not run because of an F457 ( floating Point Divide ) Function doesn't calculate or gives an error.
The calculation is 32400 divide by 60 and returns with 0.000000 in D256

I had a chat with the Omron helpdesk, emailed the program, and when they do a simulation, everything works fine.
Unfortunately they could not tell me why it isn't working in the PLC program at the machine.

I also tried to replace the F457 with a MOVF where I move 540 into D256.
The strange thing is that this instruction also gives a 0 when monitoring D256.

Anyone an idea?
 
I use /F(457) all the time in CJ's a CP's and never had a problem with it. Is something else writing to either D256 or D257?? The result from /F will be a floating point number which uses two consecutive D words.
 
I double checked for double use, and couldn't find anything.
Again, the complete program has worked for years in the old PLC, and is just copy / past in the new PLC....
 
What happens when you do a simulation?
Can you post your code here for us to look at?
Also, I’ll assume the 32400 & 60 are variables rather than constants?
If they are constants, then why not just start with the result??
I know it worked previously, just saying...
 
I can't do a simulation, it's grayed out in software, maybe it has something to do with the trail version of my software.
The Omron support engineer did a simulation where it worked as it should be.
The 32400 is a variable, the 60 is fixed.
I also tried a MOVF instruction where I move the result in the destination, even here I get a zero in the destination...
 
Change the divisor from &60 to +60.0 and possible declare the D250 variable as a REAL. Currently it is a UINT
 
When declaring D250 as a real, D251 becomes part of the symbol assigned to D250.
You may want to verify that all calculations use the proper type (REAL, INT, etc.) and that proper conversions are done. I do not think you can mix data types in the same instruction
 
AJZ said:
When declaring D250 as a real, D251 becomes part of the symbol assigned to D250.
You may want to verify that all calculations use the proper type (REAL, INT, etc.) and that proper conversions are done. I do not think you can mix data types in the same instruction
Click to expand...

You might be right, but in the old PLC this program worked perfect.
I changed the old PLC back to verify this...

But off course I'll double check this also.
 

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