Me again Tim!
Tim Ganz said:
...extended forcing...it appears you can use it to force the value in a data file and it won't be overwritten by program logic?
That's correct.
Tim Ganz said:
...Am I understanding the usage of this correctly?...
I don't think so?
Tim,
Extended Forcing is exclusively used for data files assigned to Block Transfers, which use the Block Transfer Read (BTR), or Block Transfer Write (BTW) instructions. Or if using a 1771-SDN, a CIO read or write instruction. It allows you to force Remote I/O, such as Discrete I/O over DeviceNet, or Analog I/O. The data files (B, N, A, D), which may be forced, should only be configured and used in these Block Transfer instructions. Any non-block transfer data, assigned in an Extended Force file, will be forced to zero at the end of the scan.
So it's not for general data file forcing, as I think you were assuming?
Tim Ganz said:
...Does RsLogix 5000 have a feature that does the same thing?
In RSLogix5000, you can use the 'Force Mask' column to force INT, SINT, DINT, REAL and BOOLEAN data types. You can only enable and disable forces at the controller level.
Note: Be careful when forcing tag values using the 'Force Mask' column. If you forget to remove force values, and you perform a "Find All Forces", this will only search for forced instances of tags within subroutines, and not the forces enabled for tags in their 'Force Mask' entry.
Always double-check the 'Force Mask' column when finished if you do not want unintended forces to remain. You can also filter the tag browser view to show only the tags which 'Can Be Forced'.
When I/O or produced or consumed tags are forced, the logic which may normally manipulate their values, is ignored.
George
