SLC500 How to read an N7:0 integer file

[tooslow]

Ex If I Read from Integer file N7:0
N7:0 is an 8 point input card , input 0 and 2 are on , rest off
When I look at :
N7:0 -7 6 5 4 3 2 1 0 I see decimal numbers
How do I interpet the Data ?

 

[Steve Bailey]

N7:0 is an 8 point input card

I think that's the source of your confusion. N7 is an integer file. N7:0 is the first word in the N7 file.
Input modules in the SLC are mapped into Input memory (I), not integer memory (N). The input points from the module in slot number 7 are addressed I:7.1/0 through I:7.1/7

 

[kamenges]

Is that an 8-pt digital input or 8-pt analog input? I am going to assume digital.

In the SLC5 N-files are integer files. N7:0 designates the first INTEGER in the N7 file. You want to look at the bits in the integer, specifically bits 0-7. I don't have Logix500 in front of me but I THINK you can select to view N7:0 as its combination of bits. Look for a pulldown selection where you can select stuff like "Decimal" or "Hex" and select the "Binary" or "Bool" selection.

Keith

 

[tooslow]

N7:0 is the word and N7:0/0 is the first bit correct?
What is the function of the 'Control Block' ?

 

[I_Automation]

Taking the 8 input card being in slot 7 of the rack look at the first pic below.


The inputs would be addressed as I:7.0/0 to I:7.0/7


The 7th data file of integers (N7:x) is just to hold numbers for your use in the program. See pic 2 below.


You can address the individual bits of an integer (N7:0/0) but this is mostly used for moving bit values in a group to another PLC or a HMI or other monitoring system. It might be for a quick check to see if the value is at a minimum level. Plus I have seen it used by a centerless grinder OEM that didn't want to confuse their people with binary value training so they gave them a list of values to add and enter when the machine had certain options or features. (IE - Oil Lube = 1, Grease lube = 2, Self cleaning = 4, automatic feed = 8, etc that really just set a bit for that feature)


EDIT: A control block is used internally by the PLC for messaging or sequence operations and not normally anything you would be reading or manipulating without years of experience in those

 

[Ken Moore]

Is this input module located in another PLC? Do you have a MSG block? How is the data being written to N7:0?