iFix IGS & ControlLogix rounding problem

Hi There,
This is the situation. I got a ControlLogix connected to iFix 4.5 using IGS driver. In the iFix Application I have a button that when clicked send data to the PLC through IGS. The problem is that data of datatype AO (Analog Output) from iFix is being rounded no matter that the tag at the PLC is REAL.

Any help or idea on this?

Thanks
Carlos

What is the preciesion of the number that is being written. 32bit reals only have a precision of 5 decimal places. I am of course assuming that the Anaolg Outpout is a Float/Real datatype as well.

Thanks Fred for the reply. The issue is that if I write 0.75 the ControlLogix read it as 1.00 if I write 1.5 the PLC reads 1.00 for 0.50 PLC reads 0.00.

I thinks this explain more clear my situation.

Is the item defined in the controllgix as a real or are you just making the tag in IGS a real. Also have you set andy signal conditioning on the analog output that might we changing the value written to the PLC? Lastly of you go into the IGS (Help | About| what version is it?

I am not familiar with the ifix HMIs, but the ControlLogix is quite capable of handling Reals.
This would appear to be a problem at the ifix end. Analogs were traditionally Integer.
Can you change the Data Type in the ifix? If not, perhaps you could enter it as a scaled integer, and divide that number from another Tag into your real tag in the ControlLogix. (i.e. 542 then divide by 100 for 5.42)

Stu......

Are you pushing the data down in VBA or are you entering the data through a numeric data link object via the screen? If the former, check your VBA code to ensure you aren't throwing the analog data into an inadequate data type (and truncating / rounding your data).

Also try adding the @Float specifier to the end of your IO address field in the iFix database tag

ie: Channel.Device.AnalogRegister@Float

Fred,
The tag in the controllogix is defined as Real and on IGS I just AutoCreated database. IGS version 7.40

kdcui,
Thanks for your reply. I'm entering the value via dataentry. Also I tried entering it directly through the PDB on iFix. I'll verify the VBA code generated when using dataentries and also add the @Float as you recommended. I'll get back to you as soon as possible with the results.

Thanks All

Thanks kdcui for you help on this issue. The problem was solved adding the @FLOAT to the IO address on iFix PDB.

Glad to hear!

I know there are some cases where the @ type specifiers aren't needed, but I know there are cases (like yours) where it will truncate for some reason. In our database not every address have a specifier at the end of the IO Addy.

EDIT:
I asked a colleague of mine about this.

Apparently this is an option in Device properties window in IGS for Logix processors.
It is not needed for PLC5 / SLC since the name of the data register you are writing to specifies the type (N = integer, B = boolean, F = float etc)

However since your CLX tags can be anything, the IGS doesn't know what type the data is unless you specify "@Type," otherwise it defaults to the Default Type as configured in the Controller Properties window, in the Logix Options tab.

I'm guessing your default is set to Short or Long (integer types). If you change it to Float you will not have to add the @Float (but everything would now default to Float).

Valid types are:

@Float
@Long
@Boolean
@Char
@Byte
@Short
@Word
@DWord
@String
@BCD
@LBCD

Thanks

kdcui said:

It is not needed for PLC5 / SLC since the name of the data register you are writing to specifies the type (N = integer, B = boolean, F = float etc)

Click to expand...

Interestingly, I learned this "trick" because my PLC5's negative values weren't being read by iFix.