RsLogix 500 file

I am sure there is an easy answer to this problem. However, i am fairly new to Allen Bradley PLC. The problem is that I would like to make some changes to an existing application. So i was able to upload the original plc program from a Micrologix 1000 PLC unto my computer. But i cant seem to adjust the data files element because the field is greyed out. Do i have to create a new project? Or is there some option that i am overlooking? Thanks in advance!!

I'm sure someone more knowledgeable about Micrologix will be along but, I think to be able to change data table sizes you need to have the processor in program mode (or be offline). At least, this is true with SLC-5/x.

Ker25:

Here's right from the Logix500 on-line help:

MicroLogix 1000 controllers allow you eight default data files as defined below. There are no user-defined data files.

MicroLogix 1200 and 1500 controllers support up to 256 (0-255) data files. The first eight data files have default file types as described in the table below. The remainder of the files are user defined. (Note: Although the controller allows up to 256 elements in a file, it may not actually be possible to create a file with that many elements due to the user memory size in the controller.)

File # File Type
O0 Output
I1 Input
S2 Status
B3 Bit
T4 Timer
C5 Counter
R6 Control
N7 Integer

Thanks for the info!! I guess i am limited due to the memory size in the controller. I was hoping to increase the number of elements in B3(currently 32 elements) but i will try to work arouund it.

In all the other SLCs and MicroLogix, you can change the size of the data tables and define new ones offline.

The MicroLogix 1000 has only 1K of user memory, and the Data File side of it is all pre-allocated. That B3 file cannot be made any larger.

You can use Bits inside a N7 file in virtually the same way as in a B-file, so you might look at the Usage display for N7 and find out where there is available memory.

I was thinking about using the N7 files. But i wasnt sure if i can use the BSL(Bit Shft Left) command with N7.

When in doubt, try it out...
RSLogix will tell you in the lower left corner of the screen if you made an invalid entry...and again when the file is verified.

Ker25 said:

I was thinking about using the N7 files. But i wasnt sure if i can use the BSL(Bit Shift Left) command with N7.

Click to expand...

You can, as long as you address to the bit or word level, whichever the instruction field is looking for.