Citect V5.50 and PLC s7-200, Write a real number to an address memory

danghuyhoang

Member
Join Date
Apr 2006
Location
vietnam
Posts
19
I am using PLC S7-200 Cpu 215 with COM1 of my computer.
I am having problems creating a real number for VD332 address in memory of PLC.I use command "KETTLE_TEMP=ArgValue1".
I want to write a real number (ex :0.20) to VD332 address .I attach a file what I have done.I have communicated with PLC through COM1.But I cannot understand why I cannot write a real number to an address in memory of PLC to turn on Q0.1 so I am hoping everybody can Help.Please help me .
 
danghuyhoang said:
I am having problems creating a real number for VD332 address in memory of PLC.
Maybe the reason is that you don't use a real number in your PLC program, but a double integer. If you want to compare to a real number, you'll need to use the instruction ==R in stead of ==D. The number you're comparing to should then be 15.0 in stead of 15.

And in Citect you'll have to declare your tag KETTLE_TEMP as REAL (or FLOAT, I'm not sure because at this moment I can't check it out) in stead of DOUBLE.

Kind regards,
 
Dear sir!
Firstly, Thanks to MR jvdcande. Yes,I have tried more way but I still am not successfull.I also don not understand why I can not write(or read ) an long integer(eg :15)to VD332.Therefore I think This is the same(can not write or read a real number) if I do with a real number.My attach file is test1.zip.May be something wrong (if I like testing with an integer number)?
Please help me.Hope see Mr soon
Kind regards,
 
Last edited:
Hi There,

I have had a look at the screen dumps you have put up in your message. I noticed that in your Variable.dbf entry you are scaling back 10,000 to 1,000 is this what you want to do. I would change the Raw Full Scale Value to match the engineering full scale value, this will take care of the scaling issue.

The other issue, not being able to write a decimal point value to the PLC from Citect. Your screen dumps look correct except for the Key Sequence. Because you have a number ####.# (6 characters) you have to change the Key Sequence to ######ENTER. This is because the "#" represents a character.

I hope this helps you out.

Regards,

Andrew
 
Hi Dang,

Glad to help. I have had the same issue with floating point number entry cause me problems in Citect before.

Cheers,

Andrew Butcher
 

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